As seen in the picture, I have a slime type growth on this piece of live rock, and cannot figure out what it is, or what it's from. The other side is covered with UFO Hornets and Jungle Juice Zoa's. There are pineapple sponges along the rock as well if that shows any indication of the overall health of the tank. The piece of rock here is several years old as well, all of the encrusted worms are from a tear down years ago. Any ideas on what it is, or what's causing it?