fossil

Fossil-bearing limestone with ammonite

Calcitic limestone containing an ammonoid fossil (Subclass Ammonoidea; exact genus uncertain)

AI-generated identification · may be incorrect

The host is typically gray-brown, dull to earthy, and composed mainly of calcite (Mohs 3); the fossil shows a planispiral, chambered shell with ribbing. Calcite has rhombohedral cleavage and reacts vigorously with dilute hydrochloric acid.

Identified September 4, 2026More fossil →

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At a glance

Common name: Fossil-bearing limestone with ammonite
Scientific name: Calcitic limestone containing an ammonoid fossil (Subclass Ammonoidea; exact genus uncertain)
Category: fossil
Identified: September 4, 2026
Method: Standard

AI Estimated Value

About $15–$100 for a common small specimen; $100–$500+ if the fossil is exceptionally complete, prepared, large, or from a documented locality.

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

Marine carbonate sediment lithified into limestone; the ammonoid lived during the Paleozoic–Mesozoic, approximately 400–66 million years ago, though the exact age cannot be determined from the image.

Uses & applications

Used primarily for collecting, education, and display; fossil limestone may also be cut for decorative objects, but this specimen is more valuable as a natural-history piece than as construction stone.

Geological facts

Ammonoids are extinct cephalopod relatives of modern nautiluses, squid, and octopuses. Their chambered shells are commonly preserved as calcite replacements or molds.

Field identification & locations

Identify the fossil by its coiled, ribbed spiral and septate chambers; test the matrix with acid only on an inconspicuous spot. Common deposits occur worldwide, especially in former marine basins.