Rock Identifier
Polished ammonite fossil (Ammonoidea; likely a polished ammonite shell fossil, with the exact genus undeterminable from the image) — fossil
fossil

Polished ammonite fossil

Ammonoidea; likely a polished ammonite shell fossil, with the exact genus undeterminable from the image

AI-generated identification · may be incorrect

Dark, glossy, roughly spherical display specimen with visible curved shell chambers; hardness and mineral composition depend on preservation, commonly calcite or silica replacing shell material in limestone or shale.

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Physical properties

Dark, glossy, roughly spherical display specimen with visible curved shell chambers; hardness and mineral composition depend on preservation, commonly calcite or silica replacing shell material in limestone or shale.

Formation & geological history

Ammonites were marine cephalopods that lived from the Devonian to the end of the Cretaceous (about 419–66 million years ago); their shells were buried in sediment and fossilized, then polished.

Uses & applications

Collected and displayed as a fossil; polished ammonites are also used in decorative objects and jewelry.

Geological facts

The curved internal partitions of an ammonite shell form distinctive chambers, though polishing and the viewing angle obscure detail here.

Field identification & locations

Look for a coiled shell and chamber divisions; common fossil sources include Morocco, Madagascar, and parts of Europe and North America. The pictured specimen’s locality cannot be determined visually.

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