fossil

Fossil shell fragment, likely bivalve or brachiopod

Indeterminate fossilized mollusk/brachiopod; commonly calcite (CaCO₃)

AI-generated identification · may be incorrect

Gray-beige, weathered, irregularly curved shell with possible ribbing and a dull to slightly waxy luster; fossil shell material is typically Mohs 3, with calcite cleavage and specific gravity near 2.7. The image is insufficient for confident species identification.

Identified September 5, 2026More fossil →

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Physical properties

Formation & geological history

A marine shell was buried in carbonate sediment and mineralized or recrystallized during diagenesis, commonly in Paleozoic–Cenozoic sedimentary rocks. Exact age cannot be determined visually.

Uses & applications

Primarily a teaching, display, or collecting specimen; calcitic fossil material has little industrial value compared with limestone.

Geological facts

The broad curved form and layered/ridged surface suggest a partial shell rather than an igneous or metamorphic rock. Acid fizzing would support calcite, though testing may damage it.

Field identification & locations

Look for bilateral shell symmetry, growth lines, ribs, hinge structures, and a contrasting sedimentary matrix; common sources include limestone exposures worldwide. Avoid aggressive cleaning or acid tests.