Brian, Sorry to hear about the disasters. There is something you should think about. If that "emerald" has a larger claw and is actually big enough to be suspected of tearing a chocolate chip stars leg off, then it is a rock crab, not an emerald crab. They look pretty much the same when they are small, except for the claw. Rock crabs are dangerous predators, even at a small size. An emerald doesn't have a claw that is note worthy larger enough to comment about and would never be suspect in ripping up a chocolate chip star. They only ever do algae and maybe a fish food hand out or something dead. You could also have a mantis in there that has grow up a bit. Either way, mantis or rock crab or something else that has grown, a day like this happens suddenly when that predator has just grown large enough to try it. Once it finds it can, it will not stop. Other possibilities; a rock crash from digging clowns?