fossil

Fossil Coral

Scleractinia or Anthozoa (Fossilized)

Hardness: 3-4 (if calcified) to 7 (if silicified/agatized); Color: White, cream, or light gray; Luster: Dull to earthy; Structure: Distinctive parallel septa or radiating pore patterns (corallites); Cleavage: None

Hardness: 3-4 (if calcified) to 7 (if silicified/agatized)
Color: White, cream, or light gray
Luster: Dull to earthy

Identified July 20, 2026More fossil →

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Physical properties

Formation & geological history

Formed from the skeletal remains of marine polyps. Over millions of years (often Devonian to Pleistocene), the organic material is replaced by minerals like calcite or silica in marine sedimentary environments.

Uses & applications

Used primarily for educational study, fossil collecting, lapidary work (when agatized), and decorative landscaping.

Geological facts

Fossil corals provide vital data about ancient sea levels and water temperatures. Some specimens, like Petoskey stones, are actually fossilized rugose coral from over 350 million years ago.

Field identification & locations

Identify by looking for repeating geometric or 'honeycomb' patterns on the surface. Commonly found in areas that were ancient seabeds, such as the Great Lakes region or limestone quarries.