Fossilized Solitary Rugose Coral

Physical Properties

Hardness: 3-4 (Mohs scale), Color: tan to gray, Luster: dull to earthy, Structure: horn-shaped with septa radiating from the center, Composition: Calcium Carbonate (Calcite)

Formation & Geological History

Formed in warm, shallow marine environments during the Paleozoic era (Ordovician to Permian periods, approx. 488 to 251 million years ago).

Uses & Applications

Used primarily as decorative collector specimens, educational items for paleontology, and occasionally for lapidary work.

Geological Facts

They are called 'Horn Corals' because of their unique cone shape. Unlike modern corals, these were solitary organisms that lived on the seafloor rather than in massive colonies.

Field Identification & Locations

Identify by its distinct horn or cone-like shape and internal radial lines (septa). Found frequently in limestone outcrops and gravel pits across North America and Europe.

Identified on: 5/3/2026

Mode: Standard