fossil

Fossilized coral fragment

Fossil scleractinian coral; commonly calcite/aragonite replaced by calcite (CaCO₃)

AI-generated identification · may be incorrect

Tan, porous specimen with abundant small corallite pits and a dull to slightly earthy luster; hardness about 3–4, typically brittle, with no obvious cleavage. The visible honeycomb-like structure is characteristic of coral rather than igneous rock.

Identified September 7, 2026More fossil →

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Physical properties

Formation & geological history

A colonial marine coral skeleton was buried in carbonate sediment and mineralized during diagenesis, commonly over millions of years from the Paleozoic to Cenozoic. Exact age and species require microscopy and locality information.

Uses & applications

Primarily a teaching, decorative, and collector specimen; fossil coral may also be cut and polished for ornamental objects and jewelry. It has little construction value as an individual fragment.

Geological facts

Coral fossils preserve the original colony architecture, including corallites where individual polyps lived. A drop of dilute hydrochloric acid or vinegar may produce effervescence if carbonate remains exposed.

Field identification & locations

Identify it by repeated polygonal or circular corallite cavities, irregular fossil texture, and a positive acid reaction; distinguish it from pumice or vesicular lava, which lacks organized biological chambers. Fossil coral occurs in ancient limestone and raised reef deposits worldwide, including Florida, the Caribbean, Australia, and parts of Europe.