Cockle Shell (Heart Cockle)
Phylum Mollusca, Class Bivalvia, Order Cardiida, Family Cardiidae, Genus Trachycardium, Species Trachycardium egmontianum · Cardiidae (Cockle family) · Bivalve (two-shelled), whole shell, fan-shaped
Species
Trachycardium egmontianum
Shell Type
Bivalve (two-shelled), whole shell, fan-shaped
Family
Cardiidae (Cockle family)
Size
Approximately 1 to 1.5 inches, which is typical for a young or medium-sized specimen of this species. Adults generally range from 1 to 2.5 inches.
Color & Pattern
Muted gray-blue to dark grey-brown with some natural weathering and wear. The interior is not visible, but exterior coloration is heavily weathered and darkened by mineral staining.
Rarity
Common
Habitat
Shallow marine waters, typically found buried in sandy or muddy bottoms in intertidal to shallow subtidal zones, often in bays and nearshore coastal environments.
Geographic Range
Western Atlantic, extending from North Carolina through Florida, the Gulf of Mexico, and the Caribbean.
Description
A sturdy, rounded bivalve featuring strong, prominent radial ribs radiating from the umbo to the heavily scalloped margin. The exterior texture is rough and tactile due to well-defined ridges.
Key Features
Symmetrical heart-shaped profile when viewed from the side, prominent radial ribs with scaly or node-like projections, and a strongly toothed, interlocking margin.
Collector Value
Low to Moderate. While widely collected as a common beach find, heavily weathered specimens hold little monetary value and are primarily cherished by amateur beachcombers.
Condition Notes
Fair to Good condition. The shell is intact with clearly visible ribbing, though it shows significant surface wear, sun-fading, and mineral discoloration characteristic of a beach-worn specimen.
Interesting Facts
Cockles are capable of using their muscular, hatchet-shaped foot not just for burrowing into the sand, but also to leap or flip themselves away from approaching predators like starfish.
Ecological Role
Serves as an important filter feeder helping to maintain water quality, and acts as a vital food source for bottom-feeding fish, rays, sea turtles, and carnivorous mollusks.
Similar Species
Atlantic Giant Cockle (Dinocardium robustum), which is significantly larger and broader, and the Yellow Cockle (Trachycardium muricatum), which features brighter yellow or mottled color patterns.
Beach Finding Tips
Look along high-tide wrack lines on sandy ocean beaches or exposed sandbars during extreme low tides following stormy weather.