fossil

Ammonite fossil

Ammonoidea; likely a Jurassic or Cretaceous ammonite

AI-generated identification · may be incorrect

A coiled, planispiral fossil with a visible central coil and ribbed surface; the original shell is probably replaced or coated by calcite/iron oxides. Typical ammonite shell material is aragonite originally, commonly preserved as calcite; Mohs hardness about 3–4, pearly to dull luster, and chambered internal structure.

Identified August 24, 2026More fossil →

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Physical properties

Formation & geological history

Ammonites were extinct marine cephalopods. Their shells accumulated in seafloor sediments and fossilized through mineral replacement or infilling, commonly during the Jurassic–Cretaceous (201–66 million years ago).

Uses & applications

Primarily a collectible, educational specimen, or decorative object; polished examples are sometimes used in jewelry and ornamentation.

Geological facts

The spiral records the animal’s growing shell, while internal septa divided it into buoyancy chambers. The apparent ring-like coil and shell texture strongly support ammonite rather than a modern rock.

Field identification & locations

Common in Jurassic and Cretaceous marine strata, including parts of northern France, England, Germany, Morocco, and Madagascar. Around 48.9°N, 2.5°E, a fossil ammonite is geologically plausible from regional Mesozoic sedimentary formations, though exact origin cannot be confirmed from the photograph.