fossil

Bivalve Fossil (Clam)

Class Bivalvia (Mollusca)

Hardness: 3-3.5 (Calcite/Aragonite replacement); Color: Off-white, grey, or tan; Luster: Dull to pearly; Structure: Bilateral symmetry between two shells (valves), featuring concentric growth lines.

Hardness: 3-3
Color: Off-white, grey, or tan
Luster: Dull to pearly

Identified July 12, 2026More fossil →

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Physical properties

Hardness: 3-3.5 (Calcite/Aragonite replacement); Color: Off-white, grey, or tan; Luster: Dull to pearly; Structure: Bilateral symmetry between two shells (valves), featuring concentric growth lines.

Formation & geological history

Formed through the process of permineralization or replacement where the original shell material of a marine mollusk is replaced by minerals like calcite or silica over millions of years, typically in benthic sedimentary environments.

Uses & applications

Used primarily for educational study, geological dating (index fossils), and as decorative collectibles or jewelry components.

Geological facts

Bivalves first appeared in the Late Cambrian, about 500 million years ago. They are excellent environmental indicators for ancient marine and freshwater ecosystems.

Field identification & locations

Identify by the distinct fan or heart shape and concentric ridges. Commonly found in limestone, shale, or sandstone outcrops near former ancient seaways.