Can anyone tell me what this critter is. Found them on a rock of z's. Tiny, a bit larger than a grain of salt. Could not tell they were there until the atinics kicked in & they go fluorescent orange. I picked at one & it started moving, like the way snails do, around a single polyp. It has a rubbery feeling to it, squishy, no exoskeleton. I dipped the rock cuz several polyps seemed stressed, where ever these buggers were. All came off, about 8.