Rock Identifier
Fossil coral, likely solitary rugose coral (Rugosa (possibly colonial tabulate coral); calcite/aragonite replaced by calcite) — fossil
fossil

Fossil coral, likely solitary rugose coral

Rugosa (possibly colonial tabulate coral); calcite/aragonite replaced by calcite

AI-generated identification · may be incorrect

Cream-gray, porous, weathered fossil with radiating septa and central corallite features; low vitreous-to-dull luster, Mohs hardness about 3–4, and specific gravity near 2.6–2.8. The circular cross-section exposes coral skeletal structures.

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Physical properties

Cream-gray, porous, weathered fossil with radiating septa and central corallite features; low vitreous-to-dull luster, Mohs hardness about 3–4, and specific gravity near 2.6–2.8. The circular cross-section exposes coral skeletal structures.

Formation & geological history

Marine coral skeleton mineralized on an ancient seafloor, commonly during the Paleozoic Era (about 485–252 million years ago), then buried and lithified or permineralized. Exact age requires locality and microscopic study.

Uses & applications

Primarily a geological collectible, educational specimen, or lapidary material; occasionally used in polished fossil décor. It has little industrial value.

Geological facts

Rugose corals are commonly called horn corals, though this specimen’s nearly round form may represent a cross-section or a massive coral fragment. Septa radiating from a central region are characteristic of coral architecture.

Field identification & locations

Identify by radial partitions, repeated corallite patterns, and calcite hardness; distinguish from limestone by its organized biological structure. Common in Paleozoic fossil-bearing limestones worldwide, including North America, Europe, and Australia.

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
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sedimentary
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Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil