That is too weird Brian, i have 2 rocks with the same stuff on them. Ugly as all get out but Harmless. I have been trying to box them in with more noxious creatures. I have had some success with the JF Monti, sunset monti and some trumpets. I am contemplating pulling those rocks and killing them off. I have some corals that are on there also but nothing to big or expensive that can't be replaced. Also thinking about putting my hammer colony next to them not sure yet.