Chombone

A Chombone is an obstacle that resembles a giant white louse in Mario & Luigi: Bowser's Inside Story. There are two different sizes of Chombone. They only appear in the Pump Works inside Bowser's body, where, if fed with star-like shapes coming from pipes, it will slam through the floor, making more areas accesible to Mario and Luigi.

Trivia
The name "Chombone" is probably a pun of the onomatopoeia "Chomp" and bone.