fossil

Fossil oyster shell

Oyster bivalve shell, likely Ostrea or Crassostrea sp.; chiefly calcite (CaCO₃)

AI-generated identification · may be incorrect

Hardness about 3 Mohs; tan, cream, and brown, with a dull to pearly luster, layered growth bands, irregular ribbing, and shell-shaped cleavage/fracture. It is lightweight relative to rock and may fizz weakly in dilute hydrochloric acid.

Identified September 13, 2026More fossil →

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Physical properties

Formation & geological history

A marine bivalve shell preserved through burial and mineralization, commonly retaining original calcitic shell material; its age cannot be determined from the image and may range from recent to Cenozoic or older.

Uses & applications

Primarily a teaching, collecting, and decorative specimen; fossil oyster shells are also used in displays and occasionally crushed for agricultural lime or aggregate.

Geological facts

The broad curved form, concentric growth lines, and thick irregular valve strongly indicate an oyster rather than a mineral crystal or ordinary stone.

Field identification & locations

Common in marine sediments, coastal exposures, limestone, and shell beds worldwide; check for matching hinge structures, layered shell texture, and fossil matrix. Avoid prolonged acid exposure or abrasive cleaning.