Ya know, when hermit crabs find a new shell and it's too big for them they sit next to it. Others come try it and if its too big for them they sit next to it too.
But what's interesting is they line up by size, with the largest crab closest to the shell.
Finally, when a big crab comes by and the shell fits, he drops the old one and the next largest crab gets it. That second crab drops his old one and the next crab gets it, etc, etc. All the crabs in line get a new shell as soon as the crab in front of them moves into their new shell.
So, yeah. I'd watch hermit crabs all day if I could too.