fossil

Echinoid Fossil (Fossilized Sea Urchin)

Echinoidea

Hardness 3 (calcite matrix/shell composition), greyish-brown to dark tan color, dull to earthy luster, rounded disk-like shape with radial or central mouth/anus structures (periproct/peristome) visible on the test surface.

Identified July 27, 2026More fossil →

Explore Echinoid Fossil (Fossilized Sea Urchin) in the encyclopedia →

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Physical properties

Formation & geological history

Formed during the Mesozoic to Cenozoic eras as ancient marine sea urchins were buried in ocean sediment, where minerals gradually replaced the shell tissue over millions of years.

Uses & applications

Highly prized by paleontology collectors, educators, and fossil enthusiasts; used for geological studying and decorative display.

Geological facts

Echinoid fossils are commonly referred to as 'fairy loaves' or 'shepherd's crowns' in folklore due to their distinctive petrified dome shape. They are echinoderms, closely related to modern starfish and sea cucumbers.

Field identification & locations

Identified by five-fold symmetry patterns, small raised nodes where spines were once attached, and central circular openings. Commonly found in chalk deposits, limestone formations, and coastal sedimentary strata.