Source: Paizo Blog
This strange vermillion fungus clings to the moist walls, floors, and even ceilings of dungeons and caverns. When a living creature is in or near a patch of this fungus, acidic pseudopods lash out, with sickening effect.
When a living creature starts it turn in an area of or in a square next to (if it clings to the walls or the ceiling) of tentacle mold, it must make a DC 15 Fortitude saving throw; on a failed saving throw the creature takes 1 acid damage and is sickened for 1 round. Though the effect is like a poison, this is not actually a poison effect; the strange chemistry of this kind of mold makes it more alchemical in nature.