Rock Identifier
Polished ammonite fossil (Ammonite; extinct cephalopod, likely a Jurassic or Cretaceous form) — fossil
fossil

Polished ammonite fossil

Ammonite; extinct cephalopod, likely a Jurassic or Cretaceous form

AI-generated identification · may be incorrect

Fossilized, coiled shell with visible chamber partitions; the brown shell is polished, and the pale spiral likely exposes mineral-filled chambers. Original shell material and hardness vary; commonly replaced or infilled by calcite or other minerals.

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Physical properties

Fossilized, coiled shell with visible chamber partitions; the brown shell is polished, and the pale spiral likely exposes mineral-filled chambers. Original shell material and hardness vary; commonly replaced or infilled by calcite or other minerals.

Formation & geological history

Ammonites lived in marine environments and became fossilized after burial in sediment; most commercially sold specimens are roughly 66–200 million years old.

Uses & applications

Primarily a decorative and collectible fossil, often cut and polished to reveal its internal spiral.

Geological facts

Ammonites were marine relatives of modern squid and nautiluses; their chambered shells helped regulate buoyancy.

Field identification & locations

Recognize the distinctive planispiral coil and repeated internal chambers. Ammonite fossils occur worldwide in marine sedimentary rocks; polished examples commonly come from Morocco and Madagascar.

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