Yesterday, i went to another LFS and bought some live rock that the guy said came from Florida (ok cool, really don't care where it came from), anyway, this morning there were these thread like things coming off the new rock reaching to other nearby rock. When the lights were turned on, the thread like "things" began to retract seemingly back into the rock. I didn't see any creatures or anything. There seem to be four different places where the threads retracted into the rock. Weirdness. What is this???