fossil

Fossilized coral or stromatoporoid

Calcareous fossil, likely colonial coral (phylum Cnidaria) or stromatoporoid sponge; commonly calcite/aragonite replaced by calcite

AI-generated identification · may be incorrect

Gray-brown, weathered, porous specimen with irregular cavities and possible colonial growth texture; hardness about 3–4 Mohs, dull to slightly waxy luster, dense calcium-carbonate skeleton, no obvious cleavage. Exact identification is limited by the image.

Identified September 19, 2026More fossil →

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At a glance

Common name: Fossilized coral or stromatoporoid
Scientific name: Calcareous fossil, likely colonial coral (phylum Cnidaria) or stromatoporoid sponge; commonly calcite/aragonite replaced by calcite
Category: fossil
Identified: September 19, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$100+ if the fossil structure is well preserved, identified, and attractively polished.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

A marine reef-building organism formed a calcium-carbonate skeleton, later buried and lithified; many similar fossils are Paleozoic (about 541–252 million years old), though coral fossils range from Ordovician to modern deposits.

Uses & applications

Primarily a collectible and educational specimen; polished fossil coral is also used decoratively and occasionally in jewelry. It is not typically used as construction stone in this small form.

Geological facts

The holes may be original corallite or skeletal cavities enlarged by weathering and dissolution, rather than volcanic vesicles. A dilute acid test should produce effervescence if exposed carbonate is present.

Field identification & locations

Look for repeated corallite patterns, concentric laminations, or honeycomb structure; compare with local fossil-bearing limestone. Common in ancient marine limestones worldwide, including North America, Europe, Australia, and Asia.