fossil

Fossil Shell (Bivalve)

Class Bivalvia (fossilized)

Hardness varies by mineral replacement (often Mohs 3.5-4 if replaced by calcite), colors range from brown and tan to white, luster is dull to vitreous, crystal structure is trigonal/orthorhombic depending on the replacement mineral (calcite or aragonite), specific gravity around 2.7.

Identified July 31, 2026More fossil →

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Physical properties

Formation & geological history

Formed through the process of permineralization or replacement where the original shell material of an aquatic mollusk was slowly replaced by minerals like calcite, silica, or pyrite over millions of years in sedimentary marine environments.

Uses & applications

Educational purposes, fossil collecting, decorative items, and scientific study of paleoenvironments.

Geological facts

Fossilized shells provide crucial evidence for scientists studying ancient marine ecosystems, continental drift, and historical climate changes. Many are millions of years old, dating back to the Paleozoic, Mesozoic, or Cenozoic eras.

Field identification & locations

Can be identified by the distinct growth rings, radial symmetry, and preserved skeletal structure of a mollusk. Frequently found in sedimentary rock formations such as limestone, shales, and sandstone worldwide.