From Sonic Retro
It's a rabbit-like badnik that hops around while idle and will inflate its middle section when an enemy comes close. Though it's quite slow in this state and wobbles a lot, the gelatine-like belly is indestructible, bouncing a character over and over again, and only an attack to the head can destroy the badnik. Every now and then it reverts back to its idle mode, but becomes more agile. It appears in Twinkle Park for Sonic and Amy.