fossil

Fossil bivalve shell

Calcitic aragonitic bivalve mollusk shell; exact taxon cannot be determined from the image

AI-generated identification · may be incorrect

Cream-tan, ribbed, fan-shaped shell fragment with a dull to pearly luster; composed mainly of calcium carbonate (CaCO₃), typically aragonite or calcite. Mohs hardness is about 3–4; shell has layered growth lines and curved laminae rather than mineral crystals.

Identified August 19, 2026More fossil →

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Physical properties

Formation & geological history

A biological fossil formed when a clam, scallop, or related bivalve was buried and its shell preserved, often with partial mineral replacement. Geological age and depositional setting cannot be established from the photograph alone.

Uses & applications

Primarily a natural-history collectible, teaching specimen, or decorative object; shell fossils may also be used in jewelry and crafts. It has little commercial value unless exceptionally complete, identifiable, or from a notable locality.

Geological facts

The visible ridges are growth increments and/or radial ribs, useful for distinguishing bivalves from many other fossils. Carbonate shells commonly fizz weakly in dilute hydrochloric acid, though testing can damage the specimen.

Field identification & locations

Common in marine sedimentary rocks and coastal fossil deposits worldwide; identification improves with the hinge, beak, both valves, and locality information. Typical specimens sell for about $5–$30 USD; rare, complete, well-provenanced examples may bring $50–$200+.