fossil

Fossil ammonite fragment

Ammonoidea; likely a partial planispiral ammonite shell, commonly preserved as calcite or replaced limestone

AI-generated identification · may be incorrect

Typically composed of calcium carbonate (original aragonite commonly recrystallized to calcite), hardness about 3–4, gray, tan, or brown, with a dull to pearly luster and visible coiled chamber/septa patterns. The specimen appears weathered and partially mineralized.

Identified August 18, 2026More fossil →

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At a glance

Common name: Fossil ammonite fragment
Scientific name: Ammonoidea; likely a partial planispiral ammonite shell, commonly preserved as calcite or replaced limestone
Category: fossil
Identified: August 18, 2026
Method: Standard

AI Estimated Value

Approximately $10–$75 for a small common fragment; $100–$1,000+ for large, complete, attractive, or unusually preserved specimens.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Ammonites were extinct marine cephalopods that lived from the Devonian to the end-Cretaceous, about 400–66 million years ago. Their shells accumulated in marine sediments and were later lithified, mineralized, and exposed by erosion.

Uses & applications

Used primarily for collecting, education, and decorative display; polished ammonites may be used in jewelry and ornamental objects. Commercial value depends strongly on size, completeness, preservation, locality, and preparation.

Geological facts

The curved internal divisions are chamber walls, and the animal occupied the outermost chamber. Ammonites are important index fossils for dating marine sedimentary strata.

Field identification & locations

Identify it by the involute spiral form, repeated chambers, and often distinct suture lines; limestone matrix may remain attached. Common deposits occur in Morocco, Madagascar, England, Germany, Canada, and the western United States.