fossil

Echinoid Fossil (Sea Urchin Fossil)

Echinoidea

Hardness varies (around 3 to 4 on Mohs scale if replaced by calcite); color ranges from grey, brown, to dark grey; luster is dull to earthy; crystal structure is microcrystalline calcite (CaCO3).

Identified August 6, 2026More fossil →

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Physical properties

Hardness varies (around 3 to 4 on Mohs scale if replaced by calcite); color ranges from grey, brown, to dark grey; luster is dull to earthy; crystal structure is microcrystalline calcite (CaCO3).

Formation & geological history

Formed through the fossilization of marine invertebrates (sea urchins) that lived in shallow ancient seas, typically during the Cretaceous period or Paleozoic era, where their hard tests (shells) were buried in sediment and mineralized.

Uses & applications

Used primarily as educational specimens, decorative display items, and valued by fossil collectors.

Geological facts

These fossils are sometimes colloquially known as 'fairy loaves' or 'shepherd's crowns' in folklore, and they often show the distinct five-fold (pentameral) symmetry characteristic of echinoderms.

Field identification & locations

Found worldwide in sedimentary limestone and chalk deposits. Easily identifiable by their rounded, heart-like or globular shape and distinct star-like or petal-like surface patterns.