fossil

Fossilized sea urchin

Echinoid test, likely a regular sea urchin; calcite (CaCO₃)

AI-generated identification · may be incorrect

Hardness about 3 on Mohs scale, white to gray, dull to lightly polished luster, and composed of interlocking calcite plates with distinctive tubercle bumps and radial symmetry. The spherical form and repeated circular plate impressions are characteristic of an echinoid test rather than a modern stone.

Identified September 5, 2026More fossil →

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Physical properties

Formation & geological history

A marine sea urchin skeleton was buried in carbonate sediment and mineralized or preserved as calcite during diagenesis, commonly in Mesozoic–Cenozoic limestone. Exact age and species cannot be determined from the image alone.

Uses & applications

Primarily a collectible, educational specimen, or decorative object; it has no major industrial use. Intact, naturally preserved examples are valued by fossil collectors.

Geological facts

Sea urchin tests are made of many thin calcite plates that often disarticulate after death; the visible bumps are attachment points for spines. Complete spherical specimens are relatively uncommon compared with fragments.

Field identification & locations

Common in marine limestones and coastal fossil beds worldwide, especially Europe, North Africa, the Middle East, and parts of North America. Look for fivefold symmetry, rows of tubercles, plate sutures, and a lightweight calcitic feel; confirm legality of collecting locally.