fossil

Fossilized bivalve shell

Bivalvia indeterminate; likely a fossil clam or cockle

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; cream to gray-brown, ribbed shell with low vitreous to dull luster and preserved concentric growth lines. The specimen is composed mainly of fossilized calcium carbonate (original aragonite/calcite, often partly mineral-replaced).

Identified August 27, 2026More fossil →

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Physical properties

Formation & geological history

Formed when a marine bivalve was buried in sediment and its shell was preserved or mineralized during diagenesis. Its exact geological age cannot be determined from the photograph; fossil bivalves range from the Paleozoic to Recent, and this may also be a modern beach shell rather than a fossil.

Uses & applications

Primarily a collectible, educational specimen, or decorative object; not generally used in construction or jewelry.

Geological facts

Ribbing and growth lines are biological shell features, not crystalline rock textures. A true fossil commonly feels stone-like and may show mineral infill, matrix, or loss of the original pearly interior.

Field identification & locations

Found in marine sediments, beaches, limestone, and fossil beds worldwide. Test cautiously: a vinegar drop fizzing indicates carbonate, while a fresh pearly interior and lightweight feel suggest a modern shell.