So, back in January I restarted my tank with live rock from Tampa Bay Salt Water. As with all of his customers, my rock came with all manner of live creatures. Wanting to give everyone a fair chance at survival I was reluctant to just cast out any little crab I saw. Well, as a result I now have several "Red" Emerald Crabs, neat; about half a dozen smaller, reddish filter feeding type crabs, always hiding and are hard to see; and then suddenly this creature showed up!! He has tunneled under almost all of my rock, has eaten almost all of my cleanup crew and has even taken out my pesky Mantis Shrimp! So yesterday I decided it was time to go. He actually was pretty easy to catch. I have identified him as a Rock Crab and is about the size of a 50 cent piece when he is all tucked in. So it's off to the LFS with him to find a bigger, better home; hopefully for him.