Clown Missile Blaster
From the Super Mario Wiki
Clown Missile Blasters are indestructible cannons that fire clown-shaped missiles at Wario in the Wario World level, Wonky Circus. These cannons are placed in areas with a lot of enemies, the downside being that the Clown Missiles can even hurt the enemies. Usually, they fire out three Clown Missiles at a time, lessening Wario's chance to dodge the incoming attack.