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
Statue Trigger Details
The Holy Feather Altar statue accepts a single throw to spawn Caterpillar. The thrown spirit is not consumed and stays in the player's party. Any Water-type spirit at any level qualifies as the trigger; a low-level Water-type works as well as a fully evolved one.
Stone Stone shares the same statue and reacts to a Ground-type throw. Carrying both a Water-type and a Ground-type before teleporting to the altar lets a player complete both hidden spawns on the same visit.
Capture Tips
Approach the spawn from behind once it appears. Backstabbing doubles the first throw's capture rate.
Caterpillar's base capture rate is lower than ordinary wild spirits in the area, so an Advanced Gulu Ball is recommended over the Normal tier.
If the spawn despawns before being caught, leave the zone and re-trigger the statue. The mechanism is repeatable for the throw, but the hidden spirit itself is one-time per account.
Element Notes
Caterpillar reads as a Bug-type companion at launch. Bug-type matchups: strong into Grass, Dark, and Phantom; weak to Fire, Wing, and Mech. Carry coverage that handles those weaknesses if Caterpillar is the active spirit during exploration. Full chart on the Element Types page.