fossil

Fossil Shell (Bivalve)

Phylum Mollusca, Class Bivalvia

Hardness: 3-4 on Mohs scale (calcite/aragonite); Color: White to grey; Luster: Vitreous to dull; Crystal structure: Trigonal (calcite) or Orthorhombic (aragonite); Cleavage: Perfect rhombohedral in calcite forms.

Hardness: 3-4 on Mohs scale (calcite/aragonite)
Color: White to grey
Luster: Vitreous to dull

Identified July 31, 2026More fossil →

Explore Fossil Shell (Bivalve) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed through the process of fossilization where the original shell material of marine organisms is preserved or replaced by minerals (such as calcite, silica, or pyrite) over thousands to millions of years in sedimentary environments.

Uses & applications

Used in educational displays, fossil collecting, paleontology studies, and occasionally in decorative arts or jewelry.

Geological facts

Fossilized shells provide crucial evidence for scientists studying ancient marine ecosystems, past climates, and continental drift.

Field identification & locations

Found worldwide in sedimentary rock layers, particularly in ancient seabed deposits, limestone formations, and coastal cliffs. Identify by characteristic ribbed or smooth curved shell morphology.

Other fossil specimens

See all

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil

Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

fossil

Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary

Fossiliferous Limestone with Crinoid stems

Limestone (CaCO3) containing Crinoidea fossils

sedimentary