Slime Ball Ghosts are the most simplistic form of a ghost that the Ghostbusters faced. During the first level, it has no attack other than oozing along the floor at the player; upon reaching level 2, these little blobs gain the ability to leap around a few paces at a time. Once they first become animated, they are rather sluggish and need some time between leaps but as you progress through the levels, they become more and more energetic. Slime Ball Ghosts appear to be a spectral version of a single-celled organism.
The "fiery" variant are used by Wall Man boss; these blobs are unable to leap about and simply slither toward you until they fall into the fiery pit.