This week marks the 400th Shell of the Week in the Island Sun! The Amber Pen Shell, Pinna carnea Gmelin, 1791, inhabits the warm waters of the Caribbean, Florida Keys, and the East Coast of Florida. Shells in this species may reach 30 cm (about 12 inches) in length. The “top” shell edges of the living pen shell are slightly flexible, but become hard and brittle after the animal dies. Pen shells typically live buried in sandy, shallow-water areas of tropical and sub-tropical oceans, attached to a rock or shell fragment using a bundle of fibers called the byssus, shown in two views on the central part of the illustration. (A large reproduction of this image is on display in the In Focus exhibition at the National Shell Museum.)
