Dinocardium robustum
The Atlantic Giant Cockle, with its hard and sturdy shell can grow to five inches in length. It is also known as the Great Heart Cockle. If you put two halves together and look at them from the side, it looks like a heart.
A strong muscular foot allows them to burrow into sediment where they extend siphons into the water to filter for plankton and other organic material. They can also use this foot to leap away, in pole-vault fashion, from attacking predators. (Search YouTube “Cockle Foot”)
Cockles are eaten in European countries and used in chowder in the United States. Cockles are found living in shallow water and down to 100 feet deep. This species is 65 million years old.
Live shells should never be taken from any Florida State Park.