Rock Identifier
Fossil Sea Urchin (Echinoid fossil (specifically order Holectypoida or similar)) — fossil
fossil

Fossil Sea Urchin

Echinoid fossil (specifically order Holectypoida or similar)

AI-generated identification · may be incorrect

Hardness around 3 on the Mohs scale due to calcification, typically golden-brown to grey in color, with a characteristic radial symmetry and petal-like markings (ambulacra).

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Physical properties

Hardness around 3 on the Mohs scale due to calcification, typically golden-brown to grey in color, with a characteristic radial symmetry and petal-like markings (ambulacra).

Formation & geological history

Formed when ancient echinoids were rapidly buried in marine sediment, with their calcareous tests subsequently replaced by minerals like calcite or silica over millions of years.

Uses & applications

Valued primarily as a geological collectible, educational specimen, and sometimes used in decorative displays or jewelry.

Geological facts

These fossils often preserve intricate surface details of the original sea urchin test. In folklore, they were historically known as 'fairy loaves' or shepherd's crowns.

Field identification & locations

Easily identified by their rounded, dome-like shape and distinct star or petal patterns on the top surface. Frequently found in limestone and chalk deposits globally.

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Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

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Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

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Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
Porous limestone pebble (Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image) — sedimentary

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

sedimentary
Weathered fossil bone fragment (identification uncertain) (Fossilized bone; exact taxon and mineral composition cannot be determined from the image) — fossil

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil