This was a strange situation for me, but wife had left me a voicemail while I was at work and message said one of our emerald crabs had died. No big deal, but I get home and look in the tank and I see one at first and a little bit later see another. The only thing unusual was that the second one I noticed seemed very large. Called wife and asked for clarification. She says yes, one died and it's in the garbage can. I looked and it was. Look back in tank and see both crabs. One is what I expected from the two we received with the cleanup crew but the other was VERY large in comparison. I'm certain it's a hitchhiker emeral mithrax (as opposed to gorilla or stone crab) but I'm worried it might decide it likes clam mantle or coral polyps or anemone thingies. Need I worry?