fossil

Rugose Coral

Order Rugosa

Hardness varies around 3-4 (calcite), color ranges from grey to brown, vitreous to dull luster, horn-shaped solitary corallite structure.

Identified November 7, 2026More fossil →

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Physical properties

Hardness varies around 3-4 (calcite), color ranges from grey to brown, vitreous to dull luster, horn-shaped solitary corallite structure.

Formed through the fossilization of solitary coral skeletons during the Paleozoic era, particularly the Ordovician to Permian periods.

Used primarily in fossil collecting, educational displays, and occasionally in lapidary work.

Rugose corals are commonly known as horn corals due to their distinctive horn-like shape. They went extinct in the Permian-Triassic extinction event.

Identified by their conical shape and prominent septal grooves; commonly found in limestone and 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)