Gribble

A gribble /ˈgɹɪbəl/ (or gribble worm) is any of about 56 species of marine isopod from the family Limnoriidae. They are mostly pale white and small (1–4 millimetres or 0.04–0.16 inches long) crustaceans, although Limnoria stephenseni from subantarctic waters can reach 10 mm (0.4 in).