The Ponderous Ark
The Ponderous Ark, Eontia ponderosa (Say, 1822), is one of the most common shells found on the beaches of Sanibel and Captiva islands. One of the most striking features of this species is its dark-brown or black, velvet-like periostracum, the organic shell layer that covers part or the entire shell. Visiting beachgoers often confuse the periostracum of the Ponderous Ark for a layer of oil or tar that could have deposited on the white shell. Another feature that sets the Ponde