fossil

Fossil oyster shell

Fossilized bivalve shell, likely Ostrea or Crassostrea species; primarily calcite (CaCO₃)

AI-generated identification · may be incorrect

Hardness about 3 Mohs; tan, cream, and brown with layered growth rings, nacreous to dull luster, and irregular ribbed/laminated texture. It retains a curved shell form and may show partial mineral replacement or staining.

Identified September 13, 2026More fossil →

Explore Fossil oyster shell in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

A marine bivalve shell buried in sediment and preserved through diagenesis, commonly during the Cenozoic or Mesozoic; exact age cannot be determined from the image. Calcite commonly replaces or cements the original shell material.

Uses & applications

Used mainly for fossil collecting, education, and display; oyster shells may also be used as lime, soil amendment, or poultry-feed calcium when modern and uncontaminated.

Geological facts

The visible concentric bands are growth increments formed during the oyster’s life. Oyster fossils commonly occur in marine limestone, coastal sands, and uplifted former seabeds.

Field identification & locations

Identify by its asymmetric, thick, cupped valve, growth rings, and layered calcitic shell; test cautiously with dilute hydrochloric acid for effervescence. Common in marine sedimentary formations worldwide, including North America, Europe, and Asia.