Rocky Wrench

A Rocky Wrench is an enemy that first appeared in the game Super Mario Bros. 3 for the NES. You'll find them on the airship levles as they pop out under sewer caps and throw wrenches at you. You can kill one by stomping on it's head, but soon later another one will take it's place.

In the game Mario Kart DS, you'll find Rocky Wrenches on the Airship level, though they don't throw wrenches, you can still get harmed by running into one.