Bomb Spheroids are a rare and special type of Spheroid, Having a black coloration, a burning fuse, and the ability to explode like a grenade. It id possible that they have trouble moving, as they had to be pushed into place by normal spheroids before exploding
In the episode War Is the H-Word, during the Earthican attack on Spheron 1, a bomb Spheroid is used as a grenade in an attempt to kill Bender, Leela and some other soldiers. However, Bender covered it with himself, saving everyone and earning a Purple Heart.
Bomb Spheroids are one of the three known Spheroids - Spheroids, Bomb Spheroids, and Brain Balls.