They start quietly, heavy little bodies and squirming tails scuffling around on the cave floor. Then a pack forms and wrangles for a moment. Another pack forms. In the center of the floor several packs converge, nip and fight—squealing and jumping—then pile onto each other. More packs join, forming a bizarre pyramid, dubiously high. Something like a shambling singular being made of rats, roiling with little eyes and tails, crawls forward.