fossil

Fossilized rugose coral (horn coral)

Rugosa, class Anthozoa; commonly solitary horn corals

AI-generated identification · may be incorrect

The specimen is a small, tapered cylindrical fossil with closely spaced transverse growth ridges and fine longitudinal lines. Original coral skeleton was calcium carbonate (aragonite or calcite); hardness of the preserved material is typically about 3–4 Mohs, with a dull to waxy surface.…

Identified October 5, 2026More fossil →

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Physical properties

Formation & geological history

Rugose corals lived in Paleozoic seas, chiefly from the Ordovician to Permian (about 485–252 million years ago). Their skeletons were buried in marine sediment and later mineralized, often replaced or filled by calcite.

Uses & applications

Primarily collected, displayed, or used in educational collections; polished fossils may also be used decoratively.

Geological facts

Rugose corals are extinct and are often called horn corals because many solitary forms grew in a curved, horn-like shape.

Field identification & locations

Look for repeated growth bands and lengthwise skeletal structures; similar shapes can be other fossils, so identification is strongest when the coral’s internal pattern is visible. Fossils occur in Paleozoic marine limestone worldwide, including North America, Europe, and Asia.