A movie I've seen today pointed out the curious phenomenon of "King of Rats" since forgotten in Europe, fortunately. Occurred when several of these mammals, friends of the lack of hygiene, dark, sewer and life mob, were tangled together in the middle of his secret meetings.
The appearance of these intricate and inextricable knots of different beings, brothers and grime from their tails, making presage to a close the old European plague. Still, some think that this is legend, never the tails of rats were intertwined solos, and it was all due to subsequent manipulations carried out on dead rats, a maneuver designed by humans perhaps capricious and friends sensational news.
However, in a museum are preserved as a curiosity, the mummified remains of knots up 30 (30!) Rats. Surely this phenomenon ETA Hoffmann was inspired to stage the King of the Mice of Nutcracker.