Martesia striata (Linnaeus, 1758) - Wood Piddock

Measuring at up to 4 cm in length, the Martesia striata are white in color with a thin fawn periostracum. The interior of the shell is white and smooth, except for the radial groove, which shows through as a small ridge. They have beaks nearly at anterior end, and at the anterior end the valves are short, rounded and almost closed but taper and elongate posteriorly to a rounded point where the gape is wider. The posterior end is also very fragile and easily broken. There is a fine radial groove from the beaks to the ventral margin and anterior to this groove and there are numerous finely denticulated ribs. Posterior to this groove there are concentric growth rings. On both the dorsal and ventral surfaces there is a long narrow calcareous plate between the valves, which probably serves to keep them together. In addition there is a characteristic circular shield or plate over the beaks. The umbonal reflection is small and the apophysis long and thin. The ligament is very small. Pallial sinus reaches past the internal ridge. Margins smooth. They bore into driftwood (usually against the grain) and are not so uncommon. When seen along the beach, they are found in great numbers (i.e. colonies).