fossil

Fossil shell fragment, likely brachiopod or bivalve

Indeterminate fossilized carbonate shell; possibly Spiriferida (brachiopod)

AI-generated identification · may be incorrect

Cream-gray, ribbed, low-luster specimen with preserved shell sculpture; likely calcite or recrystallized calcium carbonate (Mohs 3), with variable cleavage and specific gravity around 2.6–2.8.

Identified August 9, 2026More fossil →

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Physical properties

Cream-gray, ribbed, low-luster specimen with preserved shell sculpture; likely calcite or recrystallized calcium carbonate (Mohs 3), with variable cleavage and specific gravity around 2.6–2.8.

Formation & geological history

A marine shell was buried in carbonate sediment and mineralized during diagenesis, commonly in Paleozoic–Mesozoic rocks; the exact age cannot be determined from the image alone.

Uses & applications

Primarily a teaching, collecting, and display specimen; cut or polished fossil material may be used decoratively, but this small fragment has little commercial utility.

Geological facts

The strong, regular radial ribs are characteristic of brachiopods and some bivalves. A brachiopod typically has unequal valves and a bilateral symmetry plane, while a bivalve has matching left and right valves.

Field identification & locations

Identify it by its ribbed shell form, symmetry, and reaction to dilute hydrochloric acid, which should fizz if exposed carbonate remains. Common in limestone deposits worldwide, especially Paleozoic marine strata; avoid acid testing on valuable specimens.