Digimon #001: Bommon

Baby: It has a bomb-shaped body. The fuse on its tail ignites the moment it hatches from its egg and steadily grows shorter, but because it evolves to the next generation before the fuse disappears, nobody knows what will happen if the fuse went out. It is the owner of a short-tempered personality, and it's said that when it gets in a bad mood, the progress of the fuse gets faster.