Millipedes

Millipedes are slow-crawling, round-bodied pests which have two sets of legs on each body segment. Millipedes develop best in damp and dark locations with abundant organic matter (food). They often curl up into a tight "C" shape, like a watch spring, and remain motionless when touched. The body is long and cylindrical. Millipedes can be found in piles of grass clippings, a wooded lot close to the house, excessive mulch around the house, and similar locations. Source: Wikipedia.com