fossil

Fossil brachiopod or bivalve shell fragment

Likely a fossilized, ribbed brachiopod; exact genus/species cannot be determined from the image

AI-generated identification · may be incorrect

Brown, matte, bilaterally patterned shell with radiating ribs; likely calcite originally, commonly replaced or impregnated by silica or iron minerals. Hardness about 3 for calcitic material, potentially 5–7 if silicified; cleavage is not apparent.

Identified September 2, 2026More fossil →

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Physical properties

Formation & geological history

A marine shell buried in sediment and fossilized through mineral replacement or infilling, likely Paleozoic–Mesozoic in age, though age cannot be established visually.

Uses & applications

Primarily a teaching, collecting, and decorative specimen; not generally used in construction or jewelry except as a cabochon or display piece.

Geological facts

The strong radial ribbing and compact triangular outline are characteristic of brachiopod shells, which can resemble clams but typically have bilateral symmetry on each individual valve.

Field identification & locations

Look for consistent ribs, a beak or hinge area, and shell symmetry; acid effervescence would suggest calcite, while lack of reaction may indicate silicification. Common in marine sedimentary rocks worldwide, especially limestone and shale beds.