fossil

Fossil bivalve shell

Fossilized marine bivalve; exact genus/species indeterminate from the photograph

AI-generated identification · may be incorrect

Cream, tan, and gray shell with visible growth lines and layered/hinge-like structure; likely calcite or aragonite partly replaced by calcite. Mohs hardness about 3–4, pearly to dull luster, low specific gravity, and weak or absent cleavage.

Identified August 19, 2026More fossil →

Explore Fossil bivalve shell in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

A marine mollusk shell accumulated in sediment and was buried, compacted, and mineralized during diagenesis; geological age cannot be determined without locality and matrix. The rounded shape may reflect natural abrasion or preparation.

Uses & applications

Primarily a teaching, decorative, and collector specimen; calcium-carbonate fossils can also be used in educational displays and lapidary art, but this example is not typically an industrial material.

Geological facts

The concentric growth bands record episodic shell growth, while irregular color zones commonly reflect mineral staining or replacement during fossilization.

Field identification & locations

Look for bilateral shell symmetry, growth ridges, a hinge or umbo, and sediment-filled or mineralized interiors; common in marine limestone and coastal deposits worldwide. Avoid acid testing if preservation matters, because calcitic shell material may effervesce.