I bought a couple of large pieces of LR at the LFS about 3 weeks ago. What I didin't know was that I got a little bonus (so to speak) in the deal. I found this bonus 2 days ago as it was trying to destroy my green button polyps. I could see that it was some kind of crab but did not look anything like my algae eating hermit crabs. Then I noticed some different types of growth on it's shell that I had been admiring just the night before..... pretty good camo on this critter. I have identified it as a decorator crab. Well needless to say he is no longer in my tank and my corals and other crabs are safe from this carnivore now. I also noticed that my hermit crabs are much more active again except that 1 is missing... I think he was a midnight snack. Just a warning for those of you buying LR.. you never know what else you may be getting.