Collembola are primitive wingless insects in the subclass Apterygota. They are chiefly soil and/or litter dwellers, and live off the fungi that decompose organic matter. Like other insects, they have three body parts (head, thorax, and abdomen), three pairs of legs, and one pair of antenna. Unlike most insects, they have no wings at any stage. Instead they posses a forked "tail" called a furcula, which enables them to spring out of harm's way.
They are only a few mm long at the most, and rather hard to find. However, they usually occur in large groups and can be observed walking about if the top layer of leaf litter is carefully removed.