Cockle Shell (Heart Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Trachycardium, Species: Trachycardium egmontianum · Cardiidae (Cockle family) · Bivalve, whole shell, fan/heart shape
Species
Trachycardium egmontianum
Shell Type
Bivalve, whole shell, fan/heart shape
Family
Cardiidae (Cockle family)
Size
Approximately 2 inches, which is average for this species. Adults typically range from 1.5 to 3 inches.
Color & Pattern
Pure white, uniformly sun-bleached and worn, obscuring any original brownish or yellowish mottled patterns. The interior is also a clean, matte white.
Rarity
Common
Habitat
Found buried shallowly in sandy or muddy substrates in shallow marine waters, bays, and grass flats.
Geographic Range
Western Atlantic, extending from North Carolina down through Florida, the Gulf of Mexico, and the Caribbean.
Description
A sturdy, symmetrical bivalve featuring strong, prominent radial ribs and characteristic scaly or spiny projections along the ridges (though somewhat worn on this specimen). The shell is equivalve and equilateral with a distinct heart-shaped profile when viewed from the side.
Key Features
Distinctive inflated heart-like profile when viewed from the anterior/posterior margins, paired with prominent radial ribs radiating from the umbo to the ventral margin.
Collector Value
Low to moderate commercial value. While very popular for crafts and beginner collections due to their attractive symmetry, pristine color specimens command higher interest than beach-worn white ones.
Condition Notes
Fair condition. The specimen is a whole, single valve, heavily sun-bleached to a uniform white with moderate wear on the exterior rib details. Collectibility grade is Good.
Interesting Facts
Cockles possess a muscular, axe-shaped foot that they use not only to burrow rapidly into the sand but also to leap away from approaching predators such as predatory sea stars.
Ecological Role
Serves as an important benthic filter feeder, cleaning the water column, and acts as a vital food source for bottom-feeding fish, rays, and carnivorous gastropods.
Similar Species
Giant Atlantic Cockle (Dinocardium robustum), which is significantly larger and typically more oblong rather than heart-shaped.
Beach Finding Tips
Look along high-tide wrack lines on sandy ocean-facing beaches or shallow bay shores shortly after stormy weather or heavy wave action.