fossil

Fossilized bivalve shell

Bivalvia indeterminate; likely a fossil cockle or clam shell, aragonite/calcite replaced or preserved

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; rounded, ribbed shell with alternating brown and pale bands, subdued to pearly luster, and strong radial ribs. The visible half is a valve; crystal structure is microscopic shell carbonate rather than a rock-forming crystal.

Identified August 8, 2026More fossil →

Explore Fossilized bivalve shell in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Fossilized bivalve shell
Scientific name: Bivalvia indeterminate; likely a fossil cockle or clam shell, aragonite/calcite replaced or preserved
Category: fossil
Identified: August 8, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common loose fossil shell; $30–$150+ for a complete, well-preserved, attractively polished or locality-documented specimen.

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

A marine bivalve shell accumulated in sediment and was buried; mineralization, compaction, and partial recrystallization preserved it as a fossil. Age cannot be determined from the image, but such specimens commonly range from Cenozoic to Mesozoic.

Uses & applications

Primarily used for collecting, education, décor, and jewelry or cabochons when polished; it has little industrial value as an individual specimen.

Geological facts

The ribs strengthened the shell against waves and predators, while growth lines record changing conditions during the animal’s life.

Field identification & locations

Identify it by bilateral shell symmetry, a distinct hinge area, growth lines, and radial ribs; common in marine sedimentary deposits and coastal fossil beds. Avoid acids, which dissolve carbonate shell material.