Jacques moulted overnight.
I got up this morning and found him, pink and naked, in the tank. I've had to quarantine him in the travel tank so the Tud and Martin won't bother him...and I think that may have been what happened to Bob. Crabs are soft, naked and incredibly vulnerable when they've just shed their old exoskeleton, and I'm prepared to bet that Bob got attacked whilst he was in that condition. It's my fault, really...I should have been a bit more aware and moved him to a separate tank so he could moult in safety.
Anyway, Jacques is busy eating his old exoskeleton (it's good for them) and is checking out new shells. His bottom is very...umm...odd looking, like a curly shrimp. I hope he moves into a new shell soon, it makes me nervous. I don't want him to die like Bob did......