Egg Cockle (also known as Isocardia Heart Cockle)
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Cardiidae, Genus: Vasticardium, Species: Vasticardium egmontianum · Cardiidae (Cockle family) · Bivalve (two-shelled), whole single valve, fan/globular shape
Species
Vasticardium egmontianum (or closely related Pacific/Atlantic cockle species)
Shell Type
Bivalve (two-shelled), whole single valve, fan/globular shape
Family
Cardiidae (Cockle family)
Size
Approximately 1 inch in height and width, which is average for this species. Adults typically range from 0.75 to 1.5 inches.
Color & Pattern
Base color is off-white to pale cream, featuring subtle brownish-orange dotted markings or streaks aligning with the radial ribs. The colors appear mostly natural with light beach-worn fading.
Rarity
Common
Habitat
Shallow subtidal to intertidal zones, typically burrowing in clean sand or fine gravel substrates in marine environments.
Geographic Range
Western Atlantic, from North Carolina through Florida, the Gulf of Mexico, and the Caribbean.
Description
A charming, robust globular bivalve featuring strong, prominent radial ribs radiating from the umbo to the crenulated margin. The exterior showcases an attractive sculpted texture with transverse microscopic scales crossing the ribs, giving it a sturdy and tactile feel.
Key Features
Prominent radial ribs (typically numbering around 30 to 40), inflated rounded shape, distinct umbo, and a finely toothed internal margin corresponding to the external ribs.
Collector Value
Low to moderate value. Commonly found by beachcombers and frequently included in beginner collections or sold in bulk in shell shops.
Condition Notes
Good condition with minor wear on the umbo. The margins are relatively intact with slight chipping. Overall collectibility grade: Good.
Interesting Facts
Cockles are capable of remarkable locomotion using a strong, muscular foot that allows them to leap or dig rapidly back into the sand when threatened.
Ecological Role
Serves as an important prey item for carnivorous snails, rays, and shorebirds. As filter feeders, they help maintain water clarity and benthic-pelagic coupling.
Similar Species
Prickly Cockle (Acanthocardia aculeata) and Yellow Cockle (Laevicardium laevigatum). Distinguished by the specific rib count, spine development, and overall inflation of the shell.
Beach Finding Tips
Look along sandy beaches following storm events or during low tide in the wrack line where light bivalve shells wash ashore.