fossil

Fossil sea urchin test

Echinoid test (class Echinoidea), likely a fossilized regular sea urchin

AI-generated identification · may be incorrect

A rounded, cream-colored calcareous shell with dense tubercle pores and radial symmetry; composed mainly of calcite. Mohs hardness about 3, white to beige color, dull to weakly pearly luster, and characteristic five-part echinoid structure; the visible surface appears weathered or mineralized.

Identified August 26, 2026More fossil →

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Physical properties

Formation & geological history

This is the preserved test (shell) of a marine echinoid, originally built from high-magnesium calcite plates. It was buried in marine sediment and fossilized through compaction and mineral alteration, likely during the Mesozoic or Cenozoic, though exact age requires locality data.

Uses & applications

Primarily a teaching, display, and collecting specimen; intact examples are occasionally used in jewelry or decorative objects. It has no significant industrial use.

Geological facts

The small bumps held movable spines, while the tiny paired pores housed tube feet. The fivefold body plan is a defining echinoid feature, although the original spines and internal structures are mostly absent.

Field identification & locations

Identify it by the spherical form, regular rows of tubercles, and radial echinoid symmetry; distinguish it from coral by its continuous test-like surface. Common in marine limestone and coastal fossil deposits worldwide, especially Europe, North Africa, and the Americas.