A biome's pools are mixed into one roster, and each cell cuts it by surface. A species' kind (ground, water or flying) decides which surfaces it stands on, and only an amphibious water species leaves the water. Applies whenever adding or editing a spawn pool, a species' habitat, egg groups or biomes, or how spawns and phenomena are placed.
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---
name: spawn-surfaces
description: A biome's pools are mixed into one roster, and each cell cuts it by surface. A species' kind (ground, water or flying) decides which surfaces it stands on, and only an amphibious water species leaves the water. Applies whenever adding or editing a spawn pool, a species' habitat, egg groups or biomes, or how spawns and phenomena are placed.
---
# Spawns stand on a surface
Every overworld cell is one of three surfaces (`Chunk.getCellSurface`, `SpawnSurface` in `src/data/ids/biome.ts`):
- **Land** is any cell that is not water. An open sea's islands are land.
- **Water** is a water cell in any biome, the open sea included.
- **Ice** is a water cell in a biome whose water is drawn frozen (`isIceBiome`). Ice is walked like ground.
## One roster, cut by surface
A biome's file under `src/data/biome/` may still register a land, water and ice pool, but they are mixed into one **roster** (`getBiomeRoster`), a species listed twice counting once at its heavier weight. A cell's pool is that roster cut to what can stand on its surface (`getSpawnPool`). Which of the biome's pools a species was written in does not decide where it appears.
## Three kinds
`getSpawnClass` sorts every species, in this order:
- **Flying**: Flying type, the Flying egg group, or Levitate in its ability pool. Stands on ground and water alike.
- **Water**: Water type, or the Water 1, 2 or 3 egg group. Stands only on water, unless its `habitat` is `Amphibious`, which lets it onto ground and ice as well.
- **Ground**: everything else. Stands only on ground and ice.
Two hand-picked lists in `src/data/biome/__create.ts` override the rules: `WATER_ONLY_FLIERS` (Gyarados, Mantine, Mantyke) are water rather than flying, and `DRY_LAND_SPECIES` (Skorupi, Drapion) are ground despite their egg group. Add to them rather than bending the rules.
`fitsSurface` states the placement rule. Caves cut their own pool the same way.
## Phenomena draw from a kind
Rippling water startles the water kind, a flying shadow the flying kind and a dust cloud the ground kind (`getClassPool`), whatever surface the landmark stands on. A grotto takes whatever stands on the ground.
## Amphibious
`habitat: Habitat.Amphibious` only matters for the water kind. Mark a water species amphibious when it is met on land as readily as in the water: frogs, turtles, crabs, otters, seals, the water starters. Fish, jellies, shellfish and whales stay water-only, and so does a water species with no habitat at all.
