fossil

Fossilized Rugose Coral (Horn Coral)

Order Rugosa

Hardness: 3-4 (Calcite-based), Color: Grayish-white with dark bands, Luster: Dull/Earthy, Structure: Conical or horn-shaped with radiating septa (lines), Cleavage: None (fossilized structure).

Identified July 18, 2026More fossil →

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Physical properties

Hardness: 3-4 (Calcite-based), Color: Grayish-white with dark bands, Luster: Dull/Earthy, Structure: Conical or horn-shaped with radiating septa (lines), Cleavage: None (fossilized structure).

Formation & geological history

Formed in shallow, warm marine environments during the Paleozoic era (Ordovician to Permian periods, approx. 488 to 251 million years ago). The coral skeleton was buried in sediment and replaced by minerals like calcite or silica.

Uses & applications

Primarily used for educational purposes, scientific study, and by amateur fossil collectors as a decorative or collection piece.

Geological facts

Rugose corals are known as 'horn corals' due to their resemblance to a bull's horn. Unlike modern corals, they were often solitary rather than colonial, and they went extinct during the 'Great Dying' Permian-Triassic extinction event.

Field identification & locations

Identify in the field by looking for conical shapes with distinct horizontal growth rings (rugae) and internal radiating plates (septa). Commonly found in limestone outcrops across North America and Europe.