Mecha-Koopa

Mecha-Koopas are windup contraptions designed to look like Koopa Troopas. Being machines, they are immune to fire, so you must stomp them. When stomped, they stop where they are and lie there for a while, until they wind themselves back up and start walking again. During this period they can be kicked (they arc and stop instead of sliding) or picked up and thrown. These flying Mecha-Koopas can defeat enemies. They first appeared in Super Mario World, where they only show up in the final boss battle. They are tossed down at you by Bowser, who is riding in his Koopa Clown Car. To beat Bowser, you must throw the Mecha-Koopas back at Bowser 3 times. They appear in multiple other games as semi-common enemies.