fossil

Fossilized oyster shell / oyster reef limestone

Predominantly calcite (CaCO₃), commonly fossil bivalve shells such as Ostrea or Crassostrea; matrix is bioclastic limestone

AI-generated identification · may be incorrect

Cream to tan, highly irregular layered shell fragments with cavities and a dull to slightly pearly luster; calcite hardness 3, typically non-cleaving massive material, specific gravity about 2.6–2.8. Effervesces strongly with dilute hydrochloric acid or vinegar.

Identified September 17, 2026More fossil →

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At a glance

Common name: Fossilized oyster shell / oyster reef limestone
Scientific name: Predominantly calcite (CaCO₃), commonly fossil bivalve shells such as Ostrea or Crassostrea; matrix is bioclastic limestone
Category: fossil
Identified: September 17, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$100+ for unusually complete, attractive, or locality-documented fossils.

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 from accumulated oyster shells and carbonate sediment in shallow marine, brackish, or estuarine settings, later cemented into limestone; age cannot be determined from the image and may range from Cenozoic to modern geological deposits.

Uses & applications

Used mainly for education, fossil collecting, décor, and sometimes crushed as agricultural lime or construction aggregate; generally not suitable for jewelry.

Geological facts

The folded, fluted shell surfaces and dense accumulation of individual valves are characteristic of oyster-bank deposits rather than crystalline marble or ordinary limestone.

Field identification & locations

Look for recognizable shell growth lines, layered nacre, and acid reaction; common in coastal sedimentary formations worldwide, especially former shallow-sea margins.