Rock Identifier
Ammonite Fossil (Ammonoidea) — fossil
fossil

Ammonite Fossil

Ammonoidea

AI-generated identification · may be incorrect

Hardness 3.5 to 4 on the Mohs scale, typically brown, gray, or pearly luster with a distinctive coiled cephalopod shell structure.

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Physical properties

Hardness 3.5 to 4 on the Mohs scale, typically brown, gray, or pearly luster with a distinctive coiled cephalopod shell structure.

Formation & geological history

Formed during the Mesozoic era, approximately 240 to 66 million years ago, through permineralization of marine mollusk shells in sedimentary marine deposits.

Uses & applications

Used widely in jewelry, decorative items, and as highly prized specimens for fossil collectors and educational displays.

Geological facts

Ammonites are extinct marine animals closely related to modern octopuses and squids, serving as excellent index fossils for dating rock strata.

Field identification & locations

Easily identified by their planispiral coiled shape and internal chamber partitions called septa; found globally in marine sedimentary rocks.

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Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Weathered fossil bone fragment (identification uncertain)

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