Steal An Egg's official description confirms that egg rarity, pet rarity, sizes and mutations are discovery systems. A complete static egg list should be maintained from live observations because the available sources do not provide a stable, complete catalog that can be safely copied here.
Biomes and egg catalog
The available sources do not provide a complete, verified biome list or egg catalog. The official description only confirms discovery of different eggs, pets, sizes and mutations. Do not treat an unlabeled community table as a complete list until each entry has been checked in the live experience.
How to build a trustworthy egg list
For each egg, record its biome, the prompt used to steal it, whether a guard was present, the hatch result and the date observed. Keep separate entries for an egg's size and mutation rather than merging them into its base name. This prevents a changing live-service catalog from turning one observation into a false universal table.
Until those observations are verified, use the official experience to discover eggs and the return route guide to protect each pickup.