Overview
Caterpillar (小草虫) is a hidden rare spirit in Roco Kingdom: World. It triggers at the same Holy Feather Altar statue as Stone Stone, but requires a water-type throw rather than a ground-type throw.
How to Obtain
Teleport to the Holy Feather Altar Magic Source in Old Airship Route.
Approach the statue.
Throw a water-type spirit at the statue. Caterpillar spawns around the statue.
Capture with any Gulu Ball.
See Also
Old Airship Route - spawn zone
Stone Stone - sibling statue trigger
Hidden Secrets and Collectibles - full hidden spirit list