fossil

Bivalve seashell

Calcareous shell, primarily aragonite (CaCO₃); likely a modern cockle or related bivalve

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; pale pink/white, pearly to dull luster, curved radial growth lines, and bilateral shell symmetry. The visible valve is an organic carbonate shell rather than a crystalline rock.

Identified September 4, 2026More fossil →

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Physical properties

Formation & geological history

Secreted by a marine mollusk in shallow coastal water; growth bands record seasonal development. It appears modern or subfossil, not an ancient mineralized fossil, unless the original material has been replaced.

Uses & applications

Used as a natural-history collectible, decoration, craft material, and occasionally calcium-carbonate feedstock; little jewelry value unless unusually patterned or intact.

Geological facts

Shell color commonly comes from organic pigments and can fade with sunlight or acids. Bivalves have two hinged valves, though only one is visible here.

Field identification & locations

Identify by the smooth inflated valve, concentric growth lines, and shell-like curvature; a vinegar drop would fizz because of carbonate, but damages the specimen. Common on beaches worldwide, especially temperate and tropical coasts.