Millipedes means "A thousand legs" but millipedes, although having more legs than centipedes, don't have a thousand legs, the record holder is, apparently, 750! Each of the millipedes body section has two pair of legs, except the few rings behind the head. Their antenna are elbowed and clubbed, and they constantly tap the ground while they move. Cilindroiulus has eyes, but many millipedes, especially those permanently living in the soil or in caves, lack eyes. A curious feature of millipedes eyes is that they add ocelli as they moult, so that adults have much large eyes, and likely much better eyesight, than juveniles. The ocelli are added so precisely to each moult than the growth stage can be determined in some species by counting the rows of ocelli.
During winter, Cylindroiulus moves down into the soil, and sometimes several individuals roll up together during winter or hide under bark. That is what the usually wood dwelling millipede was doing under the pot soil.
Stephen P. Hopkin, Helen J. Read. 1992. The biology of millipedes. Oxford University Press, 1992 233 pp.
Gordon Blower. 1985. Millipedes: keys and notes for the identification of the species. Brill Archive. 242 pages.