fossilized pearl

SOLOMONS, Md. — Many people know that Southern Maryland has a rich culture dating back hundreds of years, but not as many realize the bountiful history that goes back to prehistoric times.

A recent fossil pulled from Calvert Cliffs has garnered some attention from the Calvert Marine Museum and many others on social media. The following message was posted by CMM on Facebook:

“Assistant curator, Dr. Victor Perez, recently found a very interesting fossil. This is a fossil pearl and it’s the first of its kind from the Calvert Cliffs!

Unfortunately, the pearl was not found with the clam that produced it, so we are not certain what species made it. However, based on comparisons with modern pearls, it most likely came from the Quahog clam Mercenaria cuneata.

Clams produce pearls as a defense mechanism when they sense an irritant within their shell, such as a sand grain or parasite. The clam excretes a calcareous fluid that surrounds the irritant.

The fluid is continuously excreted and forms concentric layers around the irritant. There is one other type of fossil pearl known from the Calvert Cliffs, which is produced by the Panopea clam.

These pearls look very different from the one shown here.”

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