Rustbug

A rustbug is a tiny Cybertronian lifeform and nuisance that can transform into a primitive wheeled alternate mode for transportation.

Fiction

Earthforce

Starscream had brought a rustbug hoop to Earth, figuring that if it was useful on Cybertron, it could be useful there too. He was right. Bugged!

Beast Wars: Uprising

Spotting a rustbug close to his foot, Lio Convoy kicked it before it could start nibbling on him, causing it to transform and roll off. Broken Windshields