woodlouse

noun1

1. •
   Any of various small terrestrial isopod crustaceans of suborder Oniscidea, having a rigid segmented exoskeleton, usually feeding on dead plant matter and living in damp, dark places, such as under stones or bark. Several common species roll into a ball when disturbed, hence names such as pill bug and roly-poly.

   • In addition, both the woodlouse and the crayfish possess an unpaired medial nerve which runs along the whole length of the ventral nerve cord, linking adjacent ganglia. — 1995