Shell of the Week: The Lateral Mussel

Musculus lateralis (Say, 1822) is another local but uncommon mussel, probably neglected because of its small size. Reaching only 9 mm (about 0.35 inch), its shell is oval, inflated. Two radial, slanted lines divide each valve in three areas: a smooth central one, and anterior and posterior areas with strong radial ribs. The internal shell surface is faintly iridescent, with a very thin nacreous layer. That allows for the external colors to show by transparency.

The Lateral Mussel, Musculus lateralis, from Sanibel.

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