fossil

Fossilized bivalve shell

Calcitic or aragonitic mollusk shell, commonly Bivalvia; exact species indeterminate

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; cream-white, porous, dull to weakly lustrous, with layered shell structure and a pronounced hinge/valve form. Composition is chiefly calcium carbonate (CaCO₃), commonly calcite after diagenetic replacement.

Identified August 22, 2026More fossil →

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Physical properties

Formation & geological history

A marine bivalve shell was buried in sediment and mineralized or preserved during diagenesis; age cannot be determined from the image and may range from Paleozoic to Recent. The apparent split and paired-valve shape are consistent with a shell fossil, though a modern worn shell is also possible.

Uses & applications

Primarily used for education and collecting; crushed shell can serve as calcium feed, soil amendment, or aggregate, but this specimen has little industrial value.

Geological facts

The central hinge region and opposing convex valves are characteristic of bivalves. Surface pores and brown mineral staining commonly reflect weathering and iron-oxide-rich sediment.

Field identification & locations

Look for bilateral valve symmetry, hinge teeth or ligament features, growth lines, and carbonate effervescence in dilute hydrochloric acid; a modern shell may retain nacre or organic layers. Common in marine limestones, beaches, and fossil beds worldwide.