Rock Identifier

fossil

Brachiopod Fossil

Phylum Brachiopoda

AI-generated identification · may be incorrect

Hardness varies depending on replacement minerals, typically Mohs 3-5; color ranges from grey to brown; dull to earthy luster; bivalved symmetrical shell structure.

Identified October 18, 2026More fossil →

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Physical properties

Hardness varies depending on replacement minerals, typically Mohs 3-5; color ranges from grey to brown; dull to earthy luster; bivalved symmetrical shell structure.

Formation & geological history

Formed in ancient shallow marine environments during the Paleozoic era by the accumulation of hard-shelled invertebrate remains.

Uses & applications

Valued by fossil collectors, educational displays, and as index fossils for relative geological dating.

Geological facts

Brachiopods superficially resemble clams but belong to a completely different phylum with a lophophore feeding organ.

Field identification & locations

Commonly found in limestone and shale deposits worldwide, often identified by their symmetrical paired valves and distinct beak structure.

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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) — fossil

Likely fossil oyster shell

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

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

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)) — sedimentary

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) — sedimentary

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)) — fossil

Fossil oyster shell

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