fossil

Fossil coral fragment

Fossilized colonial coral, commonly Favositidae or related tabulate coral

AI-generated identification · may be incorrect

Cream to tan, porous honeycomb texture with polygonal corallite openings; mainly microcrystalline calcite, Mohs hardness about 3, dull to waxy luster, no obvious cleavage, and specific gravity near 2.7.

Identified September 8, 2026More fossil →

Explore Fossil coral fragment in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

A colonial marine coral skeleton was buried and mineralized, commonly through replacement by calcite or silica during the Paleozoic, roughly 540–250 million years ago. The visible holes are original corallite chambers rather than vesicles from volcanic rock.

Uses & applications

Primarily a teaching, collecting, and decorative specimen; polished fossil coral is sometimes used in jewelry and cabochons. It has little industrial value as an individual fragment.

Geological facts

Fossil corals can preserve remarkably detailed colony patterns and are useful indicators of ancient shallow, warm seas. Their appearance can superficially resemble weathered limestone or vesicular volcanic rock.

Field identification & locations

Identify it by the repeated, organized corallite pattern; random vesicles suggest pumice or scoria, while irregular pores suggest limestone. Common in Paleozoic marine limestones worldwide, including the Great Lakes region and parts of Morocco and Australia.