If you watch the wet sand at the shoreline just as a wave recedes, you’re likely to see wriggling little coquinas (Donax variabilis) hurrying to rebury themselves in the mud. These colorful clams, about the size of a fingernail, have abounded on Southwest Florida beaches for millennia. Fossilized coquina shells from thousands of years ago formed a kind of limestone that was turned into brick by early Spanish settlers. Coquina stone is still used as decorative landscape material today, even as the live descendants of those shells continue to dot our beaches with squirming specks of color.
Heart of Stone
Calcified coquina stone was once harvested in quarries. The soft, fresh blocks have to be left out to dry, sometimes for years, but then they harden into formidable brick.
“Coquina,” an American term that comes from the Old Spanish for “tiny shell,” is also known as the pompano shell or butterfly shell clam. When empty and open, the bright, hinged shells look like tiny butterflies.
Coquinas come in a variety of colors, including lavender, yellow, orange and white. To determine a coquina’s age, count the dark lines on the shell; each dark line represents a summer’s growth.
Because of their size, coquinas are eaten by a variety of sea creatures, including crabs and seabirds. Like most clams, coquinas use a muscular “foot” to dig themselves under the sand away from harm.
Gathering live coquinas can be a great activity for kids. So long as they’re fresh, the harvested clams can produce a tasty, briny seafood broth—just boil with celery, carrot and potato.
Because they filter nutrients from the water and represent a key point in the food chain, coquinas are a sign of a healthy, natural beach. If a shoreline needs to be replenished frequently, the creatures get buried under the dredged sand.
The “Coquina Clutch” is the signature move of the WWE’s Samoa Joe, a California wrestler with a Polynesian moniker—though coquinas are native to Caribbean and Gulf of Mexico waters.