It does look a lot like some of the nems I have. They are listed as Warty Nems, but I know they are not. Sadly, I have not been able to find out the exact nem that they are. Not much interest from FWC or any colleges in FL about identifying them. All work is being done on stoney corals at the moment. Dont get me wrong, I get that, but would be nice to know what these guys are. They have been showing up in South FL the past few years and were never seen before in these locations. Or at least seen by me in them, as I have collected in these locations going on 35 years now.
Let me see if I can get one to ball up and get a pic of it balled up. I have some in the substrate, so should not be that hard.
Also, as a side note. I do have some of them in my 180. Last rock that went into my 180 was over 2 years ago and it came from the system these nems are in. That has been the only thing added that has touched this system. All other things came from whatever and then into my coral QT. From there they sit, get inspected and then go into the 180. With that said, it appears that spores, small splits or whatever they are make take quite a while to show their face. In addition, most of the NPS nems I collect are all from the underside of rocks and live in high flow areas. Basically, they stay where it is dark and the flow can bring them food.