A hard-shelled beetle that patrols underground stages. Its thick shell makes it completely immune to fireballs — one of the few enemies Fire Mario cannot burn. It can be stomped into its shell and kicked like a Koopa, but it will eventually pop back out.
Stomp it to retract it into its shell, then kick the shell to eliminate it or chain through other enemies. Fireballs have zero effect — stomping is the only option.