fossil

Fossilized Bivalve

Phylum Mollusca, Class Bivalvia

Hardness 3-4 on Mohs scale, grayish-brown to tan color, dull luster, composed primarily of calcium carbonate.

Identified November 7, 2026More fossil →

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Physical properties

Hardness 3-4 on Mohs scale, grayish-brown to tan color, dull luster, composed primarily of calcium carbonate.

Formed through permineralization and replacement of ancient marine organism shells in sedimentary deposits over millions of years.

Valued by fossil collectors, educational displays, and scientific research for understanding prehistoric marine ecosystems.

Bivalve fossils date back over 500 million years to the Cambrian period and are crucial index fossils for dating sedimentary strata.

Identify by distinct shell valves and growth ribs; commonly found in limestone and marine sedimentary rock formations worldwide.

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Likely fossil oyster shell

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

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble

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

Fossil oyster shell

Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)