They have many legs, are cylindrical and about ¾ to 11 inches in length dark (between 36 and 400) brown or black in color. Some millipedes can roll into a ball. Their diet generally consists of decaying leaves and other plant matter. They will eat emergent seedlings. In the spring and again in the fall, they will move into unexpected places such as your home in search of a mate and to relocate. After a couple of weeks, they generally leave on their own. They are not harmful to humans.