Cactus Piranha Plant
From the Super Mario Wiki
Cactus Piranha Plants are a dark green colored variety of Big Piranha Plants with spikes on their faces that live in quicksand pits in the desert. They only appear in Mario Kart: Double Dash!! in Dry Dry Desert, where there is one Cactus Piranha Plant in the course located in the quicksand pit waiting for racers to fall in.