Stiff Penshell
| Name: | Stiff Penshell |
| Scientific Name: | Atrina rigida |
| Family: | Pen Shells |
| Taxonomic: | Pinnidae |
| ID Group: | Snails, Clams & Shells |
| Size: | up to 11 in. |
| Depth Range: | On the reef (10 – 60 ft.) |
| Sightings: | Seen sometimes |
This fan-shaped Pen Shell has 25 raised ribs with tube-like spines. Its color ranges from dark to light brown.
The Stiff Penshell partly buries itself with its narrow tip hidden in sand or coral crevices.