fossil

Fossil bivalve or brachiopod in sedimentary rock

Unidentified fossil shell impression; likely a ribbed bivalve or brachiopod preserved in shale/siltstone

AI-generated identification · may be incorrect

The specimen shows a fan-shaped, strongly ribbed shell impression in brown, greenish, and gray fine-grained rock. The fossil material is likely replaced or dissolved, leaving a mold; host rock is weakly cemented and probably has low hardness (about Mohs 3–5).

Identified August 14, 2026More fossil →

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At a glance

Common name: Fossil bivalve or brachiopod in sedimentary rock
Scientific name: Unidentified fossil shell impression; likely a ribbed bivalve or brachiopod preserved in shale/siltstone
Category: fossil
Identified: August 14, 2026
Method: Standard

AI Estimated Value

Approximately $5–$40 for a common fragment; $50–$150 or more if locality, species, preservation, and provenance are documented.

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

Formed when a marine shell was buried in sediment, then lithified and preserved as an impression or partial mineral replacement. Its geological age cannot be determined from the photograph, but similar fossils range from Paleozoic to Mesozoic strata.

Uses & applications

Primarily valued for education and collecting; fossil-bearing sedimentary rock may be used decoratively, but this specimen is too small and irregular for construction use.

Geological facts

The radial ribs are characteristic of many brachiopods and bivalves, but identifying the exact group requires seeing the complete shell, hinge, symmetry, and internal features.

Field identification & locations

Look for bedding planes, repeated shell fragments, carbonate reaction with dilute hydrochloric acid, and a distinct fossil/rock boundary; common settings include marine shale and limestone exposures. Avoid acid or cleaning until identification is complete.