A nasty monster in Doom II. Like the cacodemon, it looks like a single-eyed floating sphere, but it is gray instead of red, and is not smiling. It quickly spits out tough lost souls at you until the room is full of them. When you finally shoot it down, three lost souls emerge from its debris. Really nasty.
Don't use rockets on them unless you are really brave. You never know if a lost soul it suddenly spat out just explodes with the rocket in your face.