docs/briefs/captures/zone1_vigilant_patch_reef.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bfhdetospcaup"
+path="res://.godot/imported/zone1_vigilant_patch_reef.png-c13e4b56c466e2ab61173a145fd844d2.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://docs/briefs/captures/zone1_vigilant_patch_reef.png"
+dest_files=["res://.godot/imported/zone1_vigilant_patch_reef.png-c13e4b56c466e2ab61173a145fd844d2.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1

docs/briefs/terrain-site-zone1-gameplay.md

@@ -265,7 +265,11 @@ de contacts existant les sépare du fond.
   présence sonar. Le shader roche ajoute gazon algal sur les faces éclairées,
   croûtes corallines par plaques et éponges encroûtantes à l'ombre, le tout
   s'éteignant entre 40 et 75 m. L'optique de la colonne d'eau est partagée par
-  `water_light.gdshaderinc`.
+  `water_light.gdshaderinc`. Têtes de corail en volume (même jour) : trois
+  dômes bosselés procéduraux (massif, cerveau à crêtes, lobé) à base plate,
+  semés sur la roche douce (< 30°) de 12 à 40 m en patch reefs par bruit, une
+  `MultiMesh` par tuile et par variante, shader opaque `seabed_coral.gdshader`
+  (couleur de sommet × teinte d'instance, marbrure, même colonne d'eau).
 - Brouillard, lumière directionnelle et particules de la scène de test
   actuelle sont conservés et réglés par site.
 - Passe lumière du 2026-10-06 (`dive_site.tscn`) : l'ambiance vient d'un ciel

docs/briefs/terrain-varied-landforms.md

@@ -182,7 +182,8 @@ Plan de masse (nord en haut) :
   `terrain_showcase_canyon.png` (gradins et fond ridé), `_crevasse.png`,
   `_boulders.png`, `_spurs.png`, `_escarpment.png` (face de la falaise vue du
   pied) ; pour le Banc du Vigilant recuit, `zone1_vigilant_tombant.png`
-  (gradins du tombant) et `zone1_vigilant_plateau.png` (plateau ondulé). Les
+  (gradins du tombant), `zone1_vigilant_plateau.png` (plateau ondulé) et
+  `zone1_vigilant_patch_reef.png` (têtes de corail autour du caboteur). Les
   captures sont faites avec le shader à normal maps et ombrage de détail
   (brief du Banc du Vigilant, §7) ; brouillard et lumière restent ceux de la
   scène de site.

game/world/sites/seabed_coral.gdshader

@@ -0,0 +1,39 @@
+shader_type spatial;
+render_mode depth_draw_opaque;
+
+// Massive coral heads: opaque, vertex-coloured (mesh shade times the instance tint),
+// lit under the same water column as the seabed. INSTANCE_CUSTOM.x is a per-head
+// mottling phase; the submarine's projectors are not attenuated.
+
+#include "res://game/world/sites/water_light.gdshaderinc"
+
+uniform vec3 water_absorption_per_m = vec3(0.11, 0.04, 0.032);
+uniform float reference_depth_m = 24.0;
+uniform float minimum_daylight = 0.05;
+uniform float mottle_strength = 0.18;
+
+varying float daylight;
+varying vec3 chroma;
+varying float mottle;
+
+void vertex() {
+	vec3 world = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
+	vec3 transmittance = water_transmittance(-world.y, water_absorption_per_m, reference_depth_m);
+	daylight = water_daylight(transmittance, minimum_daylight);
+	chroma = water_chroma(transmittance, water_absorption_per_m, reference_depth_m);
+	mottle = sin(VERTEX.x * 9.0 + INSTANCE_CUSTOM.x * TAU) * sin(VERTEX.z * 7.0 + VERTEX.y * 5.0);
+}
+
+void fragment() {
+	ALBEDO = COLOR.rgb * (1.0 + mottle * mottle_strength) * chroma;
+	AO = daylight;
+	AO_LIGHT_AFFECT = 0.35;
+	ROUGHNESS = 0.8;
+	METALLIC = 0.0;
+}
+
+void light() {
+	float sun = water_sun_factor(LIGHT_IS_DIRECTIONAL, daylight);
+	float lambert = clamp(dot(NORMAL, LIGHT), 0.0, 1.0);
+	DIFFUSE_LIGHT += lambert * ATTENUATION * LIGHT_COLOR * ALBEDO * sun / PI;
+}

game/world/sites/seabed_flora_actor.gd

@@ -2,8 +2,9 @@ class_name SeabedFloraActor
 extends Node3D
 
 ## Scatters the seabed flora of a site from its height field, deterministically from a
-## seed: seagrass tufts on gently sloping sand in the lit band, sea fans on rock. One
-## MultiMeshInstance3D per terrain tile and per kind, with a visibility range, no
+## seed: seagrass tufts on gently sloping sand in the lit band, sea fans on rock, and
+## massive coral heads on the gentle rock of patch reefs. One MultiMeshInstance3D per
+## terrain tile and per kind (per variant for corals), with a visibility range, no
 ## collision and no sonar presence. Placement is pure and runs on the worker thread
 ## pool; the multimeshes are built afterwards on the main thread.
 
@@ -11,8 +12,9 @@ const TerrainHeightField = preload("res://game/domain/sites/terrain_height_field
 const SonarMaterial = preload("res://game/domain/sonar/sonar_material.gd")
 const SeabedFloraAssets = preload("res://game/world/sites/seabed_flora_assets.gd")
 const FLORA_SHADER = preload("res://game/world/sites/seabed_flora.gdshader")
+const CORAL_SHADER = preload("res://game/world/sites/seabed_coral.gdshader")
 
-enum Kind { SEAGRASS, SEA_FAN }
+enum Kind { SEAGRASS, SEA_FAN, CORAL_HEAD }
 
 const TILE_CELLS := 64
 # Seagrass: meadows on flat sand, dense to 20 m, gone by 36 m (Caribbean Syringodium
@@ -30,6 +32,19 @@ const FAN_DEPTH_MAX_M := 60.0
 const FAN_KEEP_PROBABILITY := 0.45
 const FAN_VISIBILITY_M := 170.0
 const FAN_HEADING := Vector2(0.8, 0.6)
+# Coral heads: patch reefs are the gentle (< 30 deg) rock of the sunlit band, 12 to
+# 40 m, clustered by noise; heads are 0.6 to 2.2 m across.
+const CORAL_SPACING_M := 3.0
+const CORAL_DEPTH_MIN_M := 12.0
+const CORAL_DEPTH_FADE_START_M := 30.0
+const CORAL_DEPTH_MAX_M := 40.0
+const CORAL_SLOPE_COSINE := 0.866  # cos(30 deg)
+const CORAL_REEF_THRESHOLD := 0.05
+const CORAL_KEEP_PROBABILITY := 0.55
+const CORAL_VISIBILITY_M := 150.0
+const CORAL_COLORS: Array[Color] = [
+	Color(0.72, 0.58, 0.3), Color(0.5, 0.52, 0.28), Color(0.68, 0.48, 0.36), Color(0.62, 0.6, 0.42),
+]
 const FAN_COLORS: Array[Color] = [
 	Color(0.55, 0.35, 0.62), Color(0.85, 0.42, 0.2), Color(0.8, 0.7, 0.3), Color(0.6, 0.3, 0.45),
 ]
@@ -41,6 +56,7 @@ class TilePlacements extends RefCounted:
 	var transforms: Array[Transform3D] = []
 	var colors := PackedColorArray()
 	var custom := PackedColorArray()
+	var variants := PackedInt32Array()
 
 
 var _field: TerrainHeightField
@@ -48,10 +64,12 @@ var _seed := 0
 var _assets: SeabedFloraAssets
 var _grass_material: ShaderMaterial
 var _fan_material: ShaderMaterial
+var _coral_material: ShaderMaterial
+var _reef_noise: FastNoiseLite
 var _meadow_noise: FastNoiseLite
 var _fan_noise: FastNoiseLite
-var _counts := {Kind.SEAGRASS: 0, Kind.SEA_FAN: 0}
-var _samples := {Kind.SEAGRASS: [], Kind.SEA_FAN: []}
+var _counts := {Kind.SEAGRASS: 0, Kind.SEA_FAN: 0, Kind.CORAL_HEAD: 0}
+var _samples := {Kind.SEAGRASS: [], Kind.SEA_FAN: [], Kind.CORAL_HEAD: []}
 
 
 func configure(field: TerrainHeightField, seed: int) -> String:
@@ -64,25 +82,28 @@ func configure(field: TerrainHeightField, seed: int) -> String:
 		_assets = SeabedFloraAssets.build(seed)
 	_grass_material = _material(_assets.blade_texture)
 	_fan_material = _material(_assets.fan_texture)
+	_coral_material = ShaderMaterial.new()
+	_coral_material.shader = CORAL_SHADER
 	_meadow_noise = _noise(seed + 11, 0.012)
 	_fan_noise = _noise(seed + 23, 0.03)
+	_reef_noise = _noise(seed + 37, 0.02)
 	var tiles := _tiles()
 	var grass: Array[TilePlacements] = []
 	var fans: Array[TilePlacements] = []
+	var corals: Array[TilePlacements] = []
 	for tile in tiles:
-		var grass_tile := TilePlacements.new()
-		grass_tile.cells = tile
-		grass.append(grass_tile)
-		var fan_tile := TilePlacements.new()
-		fan_tile.cells = tile
-		fans.append(fan_tile)
+		for list: Array[TilePlacements] in [grass, fans, corals]:
+			var placements := TilePlacements.new()
+			placements.cells = tile
+			list.append(placements)
 	var group := WorkerThreadPool.add_group_task(
-		_place_tile.bind(grass, fans), tiles.size(), -1, true, "seabed flora"
+		_place_tile.bind(grass, fans, corals), tiles.size(), -1, true, "seabed flora"
 	)
 	WorkerThreadPool.wait_for_group_task_completion(group)
 	for index in tiles.size():
 		_add_multimesh(Kind.SEAGRASS, grass[index])
 		_add_multimesh(Kind.SEA_FAN, fans[index])
+		_add_coral_multimeshes(corals[index])
 	return ""
 
 
@@ -102,8 +123,8 @@ func _clear() -> void:
 	for child in get_children():
 		remove_child(child)
 		child.free()
-	_counts = {Kind.SEAGRASS: 0, Kind.SEA_FAN: 0}
-	_samples = {Kind.SEAGRASS: [], Kind.SEA_FAN: []}
+	_counts = {Kind.SEAGRASS: 0, Kind.SEA_FAN: 0, Kind.CORAL_HEAD: 0}
+	_samples = {Kind.SEAGRASS: [], Kind.SEA_FAN: [], Kind.CORAL_HEAD: []}
 
 
 func _tiles() -> Array[Rect2i]:
@@ -122,7 +143,7 @@ func _tiles() -> Array[Rect2i]:
 	return tiles
 
 
-func _place_tile(tile_index: int, grass: Array[TilePlacements], fans: Array[TilePlacements]) -> void:
+func _place_tile(tile_index: int, grass: Array[TilePlacements], fans: Array[TilePlacements], corals: Array[TilePlacements]) -> void:
 	var tile := grass[tile_index].cells
 	var cell := _field.cell_size_m()
 	var origin := _field.origin_m()
@@ -134,6 +155,7 @@ func _place_tile(tile_index: int, grass: Array[TilePlacements], fans: Array[Tile
 	generator.seed = _seed * 7919 + tile_index
 	_place_grass(grass[tile_index], generator, x_min, x_max, z_min, z_max)
 	_place_fans(fans[tile_index], generator, x_min, x_max, z_min, z_max)
+	_place_corals(corals[tile_index], generator, x_min, x_max, z_min, z_max)
 
 
 ## Cheap rejections first, straight from the field arrays (cell reads, one noise read),
@@ -233,7 +255,72 @@ func _place_fans(out: TilePlacements, generator: RandomNumberGenerator, x_min: f
 		z += FAN_SPACING_M
 
 
-func _add_multimesh(kind: Kind, placements: TilePlacements) -> void:
+func _place_corals(out: TilePlacements, generator: RandomNumberGenerator, x_min: float, x_max: float, z_min: float, z_max: float) -> void:
+	var origin := _field.origin_m()
+	var cell := _field.cell_size_m()
+	var columns := _field.columns()
+	var rows := _field.rows()
+	var elevations := _field.elevations_m()
+	var materials := _field.materials()
+	var rock := SonarMaterial.Value.ROCK
+	var slope_limit := (1.0 / (CORAL_SLOPE_COSINE * CORAL_SLOPE_COSINE) - 1.0) * (2.0 * cell) * (2.0 * cell)
+	var z := z_min
+	while z < z_max:
+		var x := x_min
+		while x < x_max:
+			var px := x + generator.randf() * CORAL_SPACING_M
+			var pz := z + generator.randf() * CORAL_SPACING_M
+			x += CORAL_SPACING_M
+			var column := int(roundf((px - origin.x) / cell))
+			var row := int(roundf((pz - origin.y) / cell))
+			if px >= x_max or pz >= z_max or column < 1 or row < 1 or column >= columns - 1 or row >= rows - 1:
+				continue
+			var index := row * columns + column
+			if materials[index] != rock:
+				continue
+			var depth := -elevations[index]
+			if depth < CORAL_DEPTH_MIN_M or depth > CORAL_DEPTH_MAX_M:
+				continue
+			var rise_x := elevations[index + 1] - elevations[index - 1]
+			var rise_z := elevations[index + columns] - elevations[index - columns]
+			if rise_x * rise_x + rise_z * rise_z > slope_limit:
+				continue
+			var reef := _reef_noise.get_noise_2d(px, pz)
+			if reef < CORAL_REEF_THRESHOLD:
+				continue
+			var density := (1.0 - smoothstep(CORAL_DEPTH_FADE_START_M, CORAL_DEPTH_MAX_M, depth)) * CORAL_KEEP_PROBABILITY
+			if generator.randf() > density * clampf((reef - CORAL_REEF_THRESHOLD) * 5.0, 0.4, 1.0):
+				continue
+			var yaw := generator.randf() * TAU
+			var radius := generator.randf_range(0.35, 1.3)
+			var squash := generator.randf_range(0.7, 1.15)
+			var phase := generator.randf()
+			var variant := generator.randi_range(0, _assets.coral_meshes.size() - 1)
+			var color: Color = CORAL_COLORS[generator.randi_range(0, CORAL_COLORS.size() - 1)]
+			var elevation := _field.elevation_at(px, pz)
+			var basis := Basis(Vector3.UP, yaw).scaled(Vector3(radius, radius * squash, radius))
+			out.transforms.append(Transform3D(basis, Vector3(px, elevation - 0.08, pz)))
+			out.colors.append(color)
+			out.custom.append(Color(phase, 0.0, 0.0, 0.0))
+			out.variants.append(variant)
+		z += CORAL_SPACING_M
+
+
+## Coral heads of one tile, one MultiMesh per mesh variant.
+func _add_coral_multimeshes(placements: TilePlacements) -> void:
+	for variant in _assets.coral_meshes.size():
+		var subset := TilePlacements.new()
+		subset.cells = placements.cells
+		for index in placements.transforms.size():
+			if placements.variants[index] != variant:
+				continue
+			subset.transforms.append(placements.transforms[index])
+			subset.colors.append(placements.colors[index])
+			subset.custom.append(placements.custom[index])
+		_add_multimesh(Kind.CORAL_HEAD, subset, variant)
+
+
+func _add_multimesh(kind: Kind, placements: TilePlacements, variant: int = 0) -> void:
 	var count := placements.transforms.size()
 	if count == 0:
 		return
@@ -241,7 +328,13 @@ func _add_multimesh(kind: Kind, placements: TilePlacements) -> void:
 	multimesh.transform_format = MultiMesh.TRANSFORM_3D
 	multimesh.use_colors = true
 	multimesh.use_custom_data = true
-	multimesh.mesh = _assets.tuft_mesh if kind == Kind.SEAGRASS else _assets.fan_mesh
+	match kind:
+		Kind.SEAGRASS:
+			multimesh.mesh = _assets.tuft_mesh
+		Kind.SEA_FAN:
+			multimesh.mesh = _assets.fan_mesh
+		Kind.CORAL_HEAD:
+			multimesh.mesh = _assets.coral_meshes[variant]
 	multimesh.instance_count = count
 	for index in count:
 		multimesh.set_instance_transform(index, placements.transforms[index])
@@ -249,13 +342,13 @@ func _add_multimesh(kind: Kind, placements: TilePlacements) -> void:
 		multimesh.set_instance_custom_data(index, placements.custom[index])
 	var instance := MultiMeshInstance3D.new()
 	instance.name = "%s_%d_%d" % [
-		"Seagrass" if kind == Kind.SEAGRASS else "SeaFans",
+		["Seagrass", "SeaFans", "Corals%d" % variant][kind],
 		placements.cells.position.x / TILE_CELLS,
 		placements.cells.position.y / TILE_CELLS,
 	]
 	instance.multimesh = multimesh
-	instance.material_override = _grass_material if kind == Kind.SEAGRASS else _fan_material
-	instance.visibility_range_end = GRASS_VISIBILITY_M if kind == Kind.SEAGRASS else FAN_VISIBILITY_M
+	instance.material_override = [_grass_material, _fan_material, _coral_material][kind]
+	instance.visibility_range_end = [GRASS_VISIBILITY_M, FAN_VISIBILITY_M, CORAL_VISIBILITY_M][kind]
 	instance.visibility_range_end_margin = 20.0
 	instance.visibility_range_fade_mode = GeometryInstance3D.VISIBILITY_RANGE_FADE_SELF
 	instance.cast_shadow = (

game/world/sites/seabed_flora_assets.gd

@@ -4,17 +4,23 @@ extends RefCounted
 ## Procedural meshes and alpha-cut textures for the seabed flora, built synchronously
 ## from a seed so no asset is needed and every build is identical: a seagrass tuft
 ## (three crossed unit quads carrying a strap-blade texture) and a sea fan (one unit
-## quad carrying a branching net texture). Meshes are unit sized, y from 0 to 1.
+## quad carrying a branching net texture), and three massive coral heads (bumpy
+## domes with a flat base: boulder, brain-ridged and lobed). Meshes are unit sized,
+## y from 0 to 1.
 
 const BLADE_TEXTURE_WIDTH := 128
 const BLADE_TEXTURE_HEIGHT := 256
 const BLADE_COUNT := 5
 const FAN_TEXTURE_SIZE := 256
+const CORAL_VARIANT_COUNT := 3
+const CORAL_RINGS := 14
+const CORAL_SEGMENTS := 20
 
 var tuft_mesh: ArrayMesh
 var fan_mesh: ArrayMesh
 var blade_texture: ImageTexture
 var fan_texture: ImageTexture
+var coral_meshes: Array[ArrayMesh] = []
 
 
 static func build(seed: int) -> SeabedFloraAssets:
@@ -23,9 +29,77 @@ static func build(seed: int) -> SeabedFloraAssets:
 	result.fan_texture = _texture_from(_fan_image(seed + 1))
 	result.tuft_mesh = _crossed_quads(3)
 	result.fan_mesh = _crossed_quads(1)
+	for variant in CORAL_VARIANT_COUNT:
+		result.coral_meshes.append(_coral_head(seed + 10 + variant, variant))
 	return result
 
 
+## Dome of unit radius and unit height on a flat base, displaced by seeded noise:
+## variant 0 a boulder coral (broad bumps), 1 a brain coral (fine ridges), 2 a lobed
+## head (deep lobes). Vertex colour carries the shade (crevices darker).
+static func _coral_head(seed: int, variant: int) -> ArrayMesh:
+	var noise := FastNoiseLite.new()
+	noise.noise_type = FastNoiseLite.TYPE_SIMPLEX_SMOOTH
+	noise.seed = seed
+	noise.fractal_octaves = 3
+	var frequency := [0.9, 2.6, 0.6][variant] as float
+	var amplitude := [0.12, 0.07, 0.3][variant] as float
+	noise.frequency = frequency
+	noise.fractal_type = FastNoiseLite.FRACTAL_RIDGED if variant == 1 else FastNoiseLite.FRACTAL_FBM
+	var vertices := PackedVector3Array()
+	var colors := PackedColorArray()
+	var indices := PackedInt32Array()
+	# Rings from the top (ring 0, a single pole) down to the base rim; the base is a
+	# flat fan closed on a centre vertex.
+	var ring_vertex_count := CORAL_SEGMENTS
+	for ring in range(CORAL_RINGS + 1):
+		var polar := (PI * 0.5) * float(ring) / float(CORAL_RINGS)  # 0 at the pole, pi/2 at the rim
+		for segment in CORAL_SEGMENTS:
+			var azimuth := TAU * float(segment) / float(CORAL_SEGMENTS)
+			var direction := Vector3(sin(polar) * cos(azimuth), cos(polar), sin(polar) * sin(azimuth))
+			var bump := noise.get_noise_3d(direction.x * 3.0, direction.y * 3.0, direction.z * 3.0)
+			# Keep the rim on the ground: the displacement fades towards the base.
+			var radius := 1.0 + bump * amplitude * (0.35 + 0.65 * cos(polar))
+			var position := direction * radius
+			position.y = maxf(position.y, 0.0)
+			vertices.append(position)
+			var shade := clampf(0.78 + bump * 0.9, 0.5, 1.1)
+			colors.append(Color(shade, shade, shade))
+	for ring in CORAL_RINGS:
+		for segment in CORAL_SEGMENTS:
+			var next_segment := (segment + 1) % CORAL_SEGMENTS
+			var a := ring * ring_vertex_count + segment
+			var b := ring * ring_vertex_count + next_segment
+			var c := (ring + 1) * ring_vertex_count + segment
+			var d := (ring + 1) * ring_vertex_count + next_segment
+			if ring > 0:
+				indices.append_array([a, b, c])
+			indices.append_array([b, d, c])
+	var centre := vertices.size()
+	vertices.append(Vector3.ZERO)
+	colors.append(Color(0.6, 0.6, 0.6))
+	var rim := CORAL_RINGS * ring_vertex_count
+	for segment in CORAL_SEGMENTS:
+		indices.append_array([centre, rim + segment, rim + (segment + 1) % CORAL_SEGMENTS])
+	var normals := PackedVector3Array()
+	normals.resize(vertices.size())
+	for index in range(0, indices.size(), 3):
+		var face_normal := (vertices[indices[index + 2]] - vertices[indices[index]]).cross(vertices[indices[index + 1]] - vertices[indices[index]])
+		for corner in 3:
+			normals[indices[index + corner]] += face_normal
+	for index in normals.size():
+		normals[index] = normals[index].normalized() if normals[index].length() > 0.0 else Vector3.UP
+	var arrays: Array = []
+	arrays.resize(Mesh.ARRAY_MAX)
+	arrays[Mesh.ARRAY_VERTEX] = vertices
+	arrays[Mesh.ARRAY_NORMAL] = normals
+	arrays[Mesh.ARRAY_COLOR] = colors
+	arrays[Mesh.ARRAY_INDEX] = indices
+	var mesh := ArrayMesh.new()
+	mesh.add_surface_from_arrays(Mesh.PRIMITIVE_TRIANGLES, arrays)
+	return mesh
+
+
 ## Vertical unit quads crossed around the y axis, each 1 wide and 1 tall, UV mapped
 ## so the texture's bottom row sits on the ground.
 static func _crossed_quads(count: int) -> ArrayMesh:

tests/integration/run_site_terrain_integration.gd

@@ -20,7 +20,7 @@ const DIVE_SITE_SCENE = preload("res://game/world/sites/dive_site.tscn")
 const ZONE1_SITE_PATH := "res://content/sites/zone1_vigilant.tres"
 const SHOWCASE_SITE_PATH := "res://content/sites/terrain_showcase.tres"
 const GROOVE_PROBE_OFFSET_M := 25.0
-const TEST_COUNT := 49
+const TEST_COUNT := 51
 
 var _failures: Array[String] = []
 
@@ -279,6 +279,24 @@ func _test_zone1_site() -> void:
 	for sample in result.samples:
 		has_sand = has_sand or sample.material == SonarMaterial.Value.SAND
 	_expect(result.accepted and has_sand, "a reference scan from the zone 1 spawn reads the sand plateau")
+
+	# The calibration site lies below 40 m, so coral heads are checked on the patch reef here.
+	var flora := site.flora()
+	var coral_count := flora.instance_count(SeabedFloraActor.Kind.CORAL_HEAD)
+	_expect(coral_count > 0, "the Banc du Vigilant grows coral heads on its patch reef (%d)" % coral_count)
+	var field_for_corals := definition.height_field()
+	var corals_on_gentle_rock := true
+	for transform in flora.sample_transforms(SeabedFloraActor.Kind.CORAL_HEAD):
+		var at := transform.origin
+		var column := int(roundf((at.x - field_for_corals.origin_m().x) / field_for_corals.cell_size_m()))
+		var row := int(roundf((at.z - field_for_corals.origin_m().y) / field_for_corals.cell_size_m()))
+		corals_on_gentle_rock = (
+			corals_on_gentle_rock
+			and field_for_corals.material_at(at.x, at.z) == SonarMaterial.Value.ROCK
+			and field_for_corals.normal_at_cell(column, row).y >= SeabedFloraActor.CORAL_SLOPE_COSINE - 0.05
+			and -at.y >= SeabedFloraActor.CORAL_DEPTH_MIN_M and -at.y <= SeabedFloraActor.CORAL_DEPTH_MAX_M
+		)
+	_expect(corals_on_gentle_rock, "coral heads sit on gentle rock in the lit band")
 	site.queue_free()