These absurd-looking monsters were originally created as psychic batteries, generating free mental energy for military psionicists, but demonstrated a sharp rise in intelligence the more they were utilized and eventually evolved unique mental powers of their own. Like an infectious virus, the mind of a Jennyvex can leave replicants of itself in the minds of other creatures to tamper with their memories, personalities and emotions. This mental scrambling is accompanied by a pinkish, mottled rash that moves slowly but visibly around the body.

Jennyvex can communicate articulately through telepathy, but mental contact with one is always accompanied by itching and hiccups.