A small ribbed brachiopod, coloured bluish-grey with a notched edge to the shell. The valves fit tightly together. It is often covered in encrusting organisms and can be hard to spot. It is held to the rock by a strong ligament called the pedicle which protrudes through a hole in the upper, or pedicle, valve. can be strange shapes due to the crowded environment they prefer.

Low tide to 200m deep. Sometimes on rocks but prefers other animals such as mussels to attach to. Extremely abundant.

A filter feeder on plankton using a special organ called the lophophore, which is a band of tissues covered in cilia.

Can live detached from the substrate sometimes for years. They are also called lamp shells, because the shells when empty but still together look rather like an ancient roman oil lamp. Many children call the separated valves "witches toe nails"!

Photo Credit: Rod Morris. Photos available from www.rodmorris.co.nz