sedimentary

Echinoid Fossil (Sea Urchin Fossil)

Echinoidea (phylum Echinodermata), often preserved as Calcite (CaCO3)

Hardness: 3 (Mohs scale) for calcite replacement; Color: Light tan, grey, or cream; Luster: Dull to earthy; Structure: Five-fold symmetry (pentamerous), heart or dome-shaped, often showing internal ambulacral grooves.

Hardness: 3 (Mohs scale) for calcite replacement
Color: Light tan, grey, or cream
Luster: Dull to earthy

Identified March 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through permineralization or as a trace fossil in marine environments where sea urchins were buried in sediment. Commonly found in limestone or chalk beds, typically dating from the Jurassic to the Cretaceous periods (66 to 200 million years ago).

Uses & applications

Educational specimens, personal collections, jewelry (when polished or wire-wrapped), and used in historical studies of paleobiology and marine evolution.

Geological facts

In ancient folklore, these fossils were called 'fairy loaves' or 'shepherd's crowns' and were believed to protect homes from lightning or prevent bread from failing to rise. The five radiating lines on the top are known as 'petals.'

Field identification & locations

Identify in the field by looking for a dome or heart shape with distinct radial symmetry or 'petals' on the surface of sedimentary rocks. Frequently found in coastal areas or quarries with exposed limestone or chalk bedrock.

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