fossil

Fossilized oyster shell

Ostrea/Exogyra sp.; calcium carbonate (mostly calcite)

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; irregular, strongly folded shell surface with gray, tan, and whitish mineralized layers, dull to pearly luster, and dense calcitic shell structure. The specimen appears partially worn or mineral-replaced.

Identified August 21, 2026More fossil →

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Physical properties

Formation & geological history

A marine bivalve shell was buried in sediment and fossilized through compaction, cementation, and partial recrystallization or replacement. Exact age cannot be determined from the photograph; oyster fossils range from Paleozoic to Recent deposits.

Uses & applications

Primarily a collecting and educational specimen; fossil shell material may be used decoratively, while crushed fossil limestone can serve as aggregate or soil amendment.

Geological facts

The ridged, uneven valve and thick shell are characteristic of oysters, which commonly lived attached to hard surfaces in shallow marine environments.

Field identification & locations

Look for a curved, asymmetrical shell form, growth layers, and a hinge area; acid may weakly effervesce because of calcite. Common in marine sedimentary rocks worldwide, especially coastal limestone and marl deposits.