The Mechanical Piranha Plant is a cardboard-like verson of a Piranha Plant that appears in Waluigi Stadium in Mario Kart: Double Dash!! and Mario Kart Wii. They pop out from cardboard-like tubes and act like a real Piranha Plant, opening and closing their mouth. If you run into one, you will be temporarily stopped until you can steer your way around. Even being powered up by a Star is not powerful enough to destroy one of these and the kart will simply stop if done so. In multiplayer, they keep their mouths open as they come out of the Pipes.