Measled Cowrie or related Bittium/Ark/Venus clam, likely a young Noah's Ark or a rough-scaled Clam/Cockle species (e.g., Comb Bittersweet or Zebra Ark)
Phylum: Mollusca, Class: Bivalvia, Order: Arcida, Family: Glycymerididae, Genus: Glycymeris, Species: Glycymeris glycymeris · Glycymerididae (Dog Cockles / Bittersweet clams) · Bivalve (two-shelled clam), whole single valve, rounded to sub-circular shape
Species
Glycymeris glycymeris (Dog Cockle) or similar bivalve species with high confidence level
Shell Type
Bivalve (two-shelled clam), whole single valve, rounded to sub-circular shape
Family
Glycymerididae (Dog Cockles / Bittersweet clams)
Size
Approximately 1 to 1.5 inches, which is moderate for this species. Adults typically range from 1 to 2.5 inches.
Color & Pattern
Cream to off-white base color densely patterned with irregular brownish-red or zigzag reticulations and speckles. Natural coloring with minimal sun-bleaching. The exterior shows strong radial ribs and fine concentric growth lines.
Rarity
Common
Habitat
Shallow subtidal to moderately deep offshore waters, typically living buried in coarse sand, gravel, or shell rubble substrates.
Geographic Range
Eastern Atlantic Ocean, from the Mediterranean Sea northward to the British Isles and Norway.
Description
A sturdy, heavy-valved bivalve featuring a robust, rounded outline. The exterior exhibits a network of fine radial ribs intersecting with concentric growth lines, creating a checkered or reticulated texture. The coloration consists of warm brown zigzags and spots over a pale cream background.
Key Features
Heavy, solid sub-circular valve with a distinctive taxodont hinge (series of small, similar teeth along the hinge line) and a finely reticulated or checkered color pattern.
Collector Value
Low to moderate commercial value; commonly collected by beachcombers in Europe and the Mediterranean, frequently used in shell craft.
Condition Notes
Good condition with intact margins, natural color patterns preserved, and no major structural fractures or boring marks. Grade: Good to Fine.
Interesting Facts
Dog cockles are filter feeders that use a strong muscular foot to burrow into sandy substrates. Unlike true cockles (Cardiidae), they belong to a separate order (Arcida) characterized by their unique taxodont hinge teeth.
Ecological Role
Serves as an important food source for bottom-feeding fish, rays, and carnivorous gastropods. Contributes to benthic bioturbation through burrowing activities.
Similar Species
Other species in the family Glycymerididae, such as Glycymeris americana (American bittersweet) in the Western Atlantic, which can be distinguished by geographical origin and subtle variations in ribbing density.
Beach Finding Tips
Look along coarse sandy or shelly beaches after winter storms or rough seas, particularly during low tide when offshore debris is washed ashore.