fossil

Fossilized Oyster Shell

Ostreidae

Hardness of 3-4 on the Mohs scale, typically gray or off-white with rough or pearly luster, composed of calcite or aragonite.

Identified November 7, 2026More fossil →

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Physical properties

Hardness of 3-4 on the Mohs scale, typically gray or off-white with rough or pearly luster, composed of calcite or aragonite.

Formed through the fossilization of marine bivalve mollusks in shallow coastal waters over millions of years.

Valued by fossil collectors, used in educational displays, and studied for paleoenvironmental reconstruction.

Fossil oyster shells can date back hundreds of millions of years to the Triassic period and provide key climate data.

Found globally in sedimentary rock formations, especially in ancient marine deposits and limestone cliffs.

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)