fossil

Fossil coral fragment

Colonial scleractinian coral (commonly Favites or related genera)

AI-generated identification · may be incorrect

Likely calcite/aragonite, Mohs hardness about 3–4, tan-brown color, dull to slightly waxy luster, and porous honeycomb-like corallite structure; no prominent cleavage. The repeated polygonal cells are characteristic of coral skeleton rather than a crystalline rock texture.

Identified August 18, 2026More fossil →

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Physical properties

Formation & geological history

A marine coral colony secreted calcium-carbonate skeletons that were later buried, lithified, and commonly recrystallized to calcite during diagenesis. Exact age cannot be determined from the photograph; similar specimens range from Paleozoic to Cenozoic deposits.

Uses & applications

Used as a teaching specimen, fossil collectible, and occasionally as polished ornamental material or jewelry. It is generally not suitable as a durable construction stone in small pieces.

Geological facts

The visible honeycomb pattern records individual coral polyps and their shared colonial growth. Coral fossils can preserve ancient reef environments and indicate shallow, relatively warm marine water.

Field identification & locations

Identify it by closely spaced polygonal corallites, unlike random vesicles in volcanic rock; a dilute acid may effervesce, but testing can damage it. Common in limestone beds, raised marine terraces, and eroded coastal deposits.