Demolitions puppy is one of Spot's puppy amoeba that Plankton trains to use explosives for one of his plans. He only appears in the episode "Spot Returns."
Demolitions puppy is a tiny translucent green amoeba about the same size as Plankton. He has an antenna and three dark green spots on him, along with four legs on each side of his body, a pair of arms, and a tail. He wears a black beanie on his head, along with a black sash that has three (or more) grenades on it.