This species of millipede looks rather similar to a woodlouse, and this can often lead to some confusion in identification. Its common name refers to its habit of rolling into a tight ball to protect itself from predation and to prevent itself from drying out. It is greyish-brown to blackish in colour, with about 11 tight-fitting calcareous plates running down its body. It has numerous legs.
It feeds on various rotting plant material, and helps to recycle soil nutrients.
A common and widespread species throughout Britain, except the far north where it is absent