fossil

Sea Urchin Fossil

Echinoidea (test/fossil)

Hardness: 3 (calcite); Color: Grey, white, or mottled dark spots; Luster: Vitreous to dull; Crystal structure: Trigonal (calcium carbonate in the form of calcite plates); Cleavage: Perfect rhombohedral cleavage for individual calcite crystals; Specific gravity: 2.71

Hardness: 3 (calcite)
Color: Grey, white, or mottled dark spots
Luster: Vitreous to dull

Identified August 3, 2026More fossil →

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Physical properties

Formation & geological history

Formed through permineralization or replacement where the original calcareous test of the echinoid is preserved or replaced by minerals like calcite, silica, or pyrite, often found in marine sedimentary rock layers dating from the Ordovician period to the present day.

Uses & applications

Scientific study, educational display, and fossil collecting.

Geological facts

Fossilized sea urchins are often referred to regionally as 'fairy stones' or 'shepherd's crowns' and were historically believed to protect homes from lightning.

Field identification & locations

Found worldwide in limestone, chalk, and marine sedimentary formations; easily identified by their radial symmetry and the distinct pattern of tubercles where spines were once attached.