One of the many Prize Items introduced in Mario Kart Arcade GP is the Black Shell. It also returns for Mario Kart Arcade GP 2 and Mario Kart Arcade GP DX. The Black Shell can be thrown or deployed behind a Kart like a regular Green Shell, but instead of bouncing, it detonates on impact, dealing massive damage.
The Black Shell is great for taking out a group of opponents who are close together, as it has AOE damage. It can also be shot from behind to clear out any nearby racers.