Egg Cockle (Yellow Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Trachycardium, Species: Trachycardium muricatum · Cardiidae (Cockle family) · Bivalve, whole shell, fan or heart-shaped valve
Species
Trachycardium muricatum
Shell Type
Bivalve, whole shell, fan or heart-shaped valve
Family
Cardiidae (Cockle family)
Size
Approximately 2 inches in length and width, which is typical for a mature specimen. Adults of this species generally range from 1.5 to 3 inches.
Color & Pattern
Creamy off-white or pale yellowish base with faint, brownish-orange speckled radial markings and zigzag patterns. The coloration is natural and slightly sun-bleached on the prominent umbo.
Rarity
Common
Habitat
Found in shallow subtidal waters and intertidal zones, buried just beneath the surface of clean sand or muddy sand flats in bays and protected coastal waters.
Geographic Range
Western Atlantic Ocean, extending from North Carolina through Florida, the Gulf of Mexico, the Caribbean, and down to Brazil.
Description
A sturdy, inflated bivalve shell featuring strong, prominent radial ribs with fine, granular serrations. The outline is broadly oval to nearly circular, with a well-rounded ventral margin and a prominent, slightly curved umbo at the apex.
Key Features
Symmetrical, inflated rounded shape with numerous prominent radial ribs (usually 30 to 35) that have tiny spine-like scales or granules, especially visible toward the margins.
Collector Value
Low to moderate commercial value, but highly popular among casual beachcombers and beginner collectors for their appealing symmetry and durability.
Condition Notes
Good to Fine condition. The shell is intact with minor surface wear on the umbo. Colors are preserved relatively well, showing natural patterns without major structural damage or boring holes.
Interesting Facts
Cockles are capable of active movement using a strong, muscular, sickle-shaped foot, which they can use to leap away from approaching predators like starfish.
Ecological Role
Serves as an important filter feeder in coastal marine ecosystems, helping to clear water by consuming phytoplankton, and acts as a vital food source for bottom-feeding fish, rays, and sea birds.
Similar Species
Magnum Cockle (Dinocardium robustum), which is significantly larger and more oblong, and the Prickly Cockle (Acanthocardia tuberculata), which features much sharper, more pronounced spines.
Beach Finding Tips
Look along ocean-facing beaches and inlet sandbars in North Carolina, especially following strong storms or during extreme low tides when sand is shifted.
Notes
NC beaches