fossil

Fossil ammonite

Ammonoidea; likely a small, weathered ammonite or ammonoid internal mold

AI-generated identification · may be incorrect

Fossilized coiled shell with radiating ribs and a central whorl; shell material is commonly replaced by calcite or iron-bearing minerals. Original shell was mainly aragonite; hardness and luster vary with preservation.

Identified October 3, 2026More fossil →

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Physical properties

Formation & geological history

Ammonoids were marine cephalopods that lived from the Devonian to the end of the Cretaceous (about 419–66 million years ago). This specimen likely formed when sediment buried the shell and mineralized or preserved its imprint.

Uses & applications

Primarily collected and displayed; larger, well-preserved ammonites are sometimes cut or polished for ornaments and jewelry.

Geological facts

Ammonites are extinct relatives of modern squid and nautiluses; their ribbed, chambered shells are important index fossils.

Field identification & locations

Look for the coiled form, ribbing, and curved chamber boundaries; fossils occur in marine sedimentary rocks worldwide. The image does not show enough detail to identify its species or exact age.