Hey, doea anyone know what these are? My LFS gifted me some live rock a while back, to put in my sump. A few months since then and I notice these things growing out of it. A couple fell off while I was removing the rock and now im worried im going to have an infrstation of them in my main tank. Are they good or bad? They snapped off super easy and once out of the water for a few mins, seemed to have hairs on them . HELP