Hermit Rex has stolen Bo's shell!
I just went to check on them and feed them their fish. Rex is wearing Bo's shell. Sure, I originally brought it home thinking he'd like it, but I didn't know then that it was occupied. And now she probably had eggs.
Did he remove her forcibly? Shake her until she just left? Where has she gone? I can't find her now. There are ample shells for her, big ones that she would like, but they all seem to be empty.
For shame, Rex; that wasn't very kind of you!