fossil

Fossil sea urchin (likely regular echinoid)

Echinoid test; likely a fossilized sea urchin, class Echinoidea

AI-generated identification · may be incorrect

Calcareous skeleton (calcite), pale beige, porous and granular with repeated tubercle patterns; Mohs hardness about 3–4, dull to slightly pearly luster, fivefold radial symmetry, and brittle cleavage/fracture. The apparent depression may be damage or a natural oral feature.

Identified August 26, 2026More fossil →

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Physical properties

Formation & geological history

The original animal lived on a shallow marine seafloor; its calcitic test was buried and mineral-preserved, commonly during the Mesozoic or Cenozoic. Exact age and species require locality and close examination of the plate arrangement.

Uses & applications

Primarily a teaching, display, and collecting specimen; not generally used in construction or jewelry, though polished fossil echinoids may be set decoratively.

Geological facts

Sea urchin tests consist of interlocking plates bearing tubercles that supported movable spines. Complete globular specimens are more collectible than fragmented tests.

Field identification & locations

Identify by the regular tubercle pattern and five-part echinoid symmetry; avoid acids, which dissolve calcite. Common fossil sources include Morocco, France, England, Spain, and parts of the United States.