diff --git a/guide/age-of-four/src/simulation/__tests__/ecology-golden-vectors.test.ts b/guide/age-of-four/src/simulation/__tests__/ecology-golden-vectors.test.ts
index 267f8137..f4683d85 100644
--- a/guide/age-of-four/src/simulation/__tests__/ecology-golden-vectors.test.ts
+++ b/guide/age-of-four/src/simulation/__tests__/ecology-golden-vectors.test.ts
@@ -40,23 +40,22 @@ function makeTile(col: number, row: number, seed: number): TileState {
     ? (edgeDist === 0 ? 'deep_water' : 'shallow_water')
     : (elevation > 0.6 ? 'highland' : 'lowland')
 
-  // Initial biome: classify from climate for land tiles, terrain_id for water
-  const terrain_id = isWaterTile ? 'ocean' : 'grassland'
+  // Initial biome: classify from climate for land tiles, biome_id for water
+  const initial_biome = isWaterTile ? 'ocean' : 'grassland'
 
   const tile: TileState = {
     col, row,
     temperature,
     moisture,
     elevation,
-    terrain_id,
-    biome_id: terrain_id, // will be reclassified
+    biome_id: initial_biome, // will be reclassified
     wind_direction: Math.floor(h * 6),
     wind_speed: 0.5,
     quality: 2,
     quality_progress: 0,
     river_edges: [],
     flow_accumulation: 0.0,
-    original_terrain_id: terrain_id,
+    original_biome_id: initial_biome,
     ley_line_count: 0,
     ley_school: '',
     reef_health: isWaterTile ? 1.0 : 0.0,