I noticed these guys last night, however tonight it seems like we have more of them. They are all housed inside the same little cave, however two come out one side and another two come out the other side (left and right side of the pic). I was starting to wonder if maybe it was some sort of starfish, however i don't think so as it has never come all the way out of the cave and i figured if it was a star it would come out at some stage to feed.