Rock Identifier
Fossilized Bivalve (Phylum Mollusca, Class Bivalvia) — fossil
fossil

Fossilized Bivalve

Phylum Mollusca, Class Bivalvia

AI-generated identification · may be incorrect

Hardness varies around 3 to 4 on the Mohs scale depending on mineral replacement. Displays gray or brownish coloration with distinct radial ribs and a characteristic symmetrical shell morphology.

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Physical properties

Hardness varies around 3 to 4 on the Mohs scale depending on mineral replacement. Displays gray or brownish coloration with distinct radial ribs and a characteristic symmetrical shell morphology.

Formation & geological history

Formed in ancient marine environments when accumulating sediment rapidly buried dead mollusk shells, replacing organic material with minerals over millions of years.

Uses & applications

Valued by fossil collectors, educational displays, and used in biostratigraphy to date sedimentary rock layers.

Geological facts

Bivalve fossils date back over 500 million years to the Cambrian period. They are among the most common and easily recognizable invertebrate fossils found worldwide.

Field identification & locations

Identify by the distinct hinged two-part shell structure and growth lines. Commonly found in sedimentary formations like limestone, shale, and sandstone.

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Unidentified carbonate-rich concretion with a possible fossil inclusion

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Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

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Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
Porous limestone pebble (Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image) — sedimentary

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

sedimentary
Weathered fossil bone fragment (identification uncertain) (Fossilized bone; exact taxon and mineral composition cannot be determined from the image) — fossil

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil