fossil

Fossilized bivalve shell fragment

Bivalvia; commonly aragonite or calcite (CaCO₃), often recrystallized during fossilization

AI-generated identification · may be incorrect

White, rounded, low-luster shell with faint growth lines and an irregular broken edge; original shell hardness is about 3–4 Mohs, with brittle calcitic or aragonitic structure and prominent shell curvature.

Identified August 16, 2026More fossil →

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Physical properties

Formation & geological history

A marine bivalve shell, likely from a Cenozoic or younger sedimentary deposit, became buried in carbonate-rich sediment and was preserved by mineral replacement or recrystallization. Exact age cannot be determined from the photograph.

Uses & applications

Primarily a teaching, collecting, and decorative specimen; fossil shell material may be used in displays, jewelry, or curios, but this piece is not suitable for construction.

Geological facts

The visible concentric growth lines record shell growth, while the raised curved form indicates a valve rather than a flat limestone fragment. The tan objects at the top may be additional shell or fossil material.

Field identification & locations

Identify it by its curved shell form, growth lines, smooth carbonate texture, and lack of crystalline igneous grains; a drop of dilute hydrochloric acid or vinegar may produce effervescence if carbonate remains exposed. Fossil bivalves occur worldwide in marine limestones and sandstones.