The stiff pen shell, or rigid pen shell, is one of several species of pen shells. These mollusks have a long, triangular or wedge-shaped shell and attach to rocks or shells in sandy, shallow ocean bottoms.
Stiff pen shells can be up to 12" long and 6.5" wide. They are a brown or purplish-brown color and have 15 or more radiating ribs that fan out across the shell. They may also have erect, tubular spines.
Habitat and Distribution:
They are found on sandy bottoms in shallow water. They attach with their byssal threads, pointed end down.
Conservation & Human Uses:
- Gofas, S. 2011. Pinnidae. World Register of Marine Species (Online) Accessed on May 24, 2011
- Meinkoth, N.A. 1981. National Audubon Society Field Guide to North American Seashore Creatures. Alfred A. Knopf, New York
- Scott, S. 2011. Pen Shells Provided Ancients Byssal Threads for Fine Sea Silk (Online) Accessed May 24, 2011