My bimac crawled out about a week ago. I thought he had died and been eaten by the brittle stars in the tank bc there was no body. He had actually crawled into the sump tank. Don't ask me how, but I guess he went through the overflow tube. I just found him underneath my skimmer pump. Whew!! Catching him was not easy, and he inked. Anyway, he's back in his tank now, no worse for the wear except maybe very hungry.