Nightmare sponges

Nightmare sponges are a Scaraquan threat that defies easy classification blurring the line between undead creatures and Psychically Tainted Locations.
They are spiritual and psychic remnants of places where large numbers of Gnosispongia had their lives and souls consumed by Void demons.
Now nightmare sponges siphon the lifeforce and sanity of mortals around them both sickening their bodies while inflicting them with nightmare hallucinations about their worst fears and insecurities.
Nightmare sponges manifest in places with lots of seemingly ordinary sponges.  Much as ordinary sponges feed nutrients out of the water around them, nightmare sponges feed on the fear and pain of Scaraquans unfortunate enough to swim near them.