fossil

Echinoid Fossil

Echinoidea class

Hardness: 3-4 (calcite), Color: Greenish-brown, Luster: Vitreous to dull, Crystal structure: Trigonal (calcite replacement)

Identified November 9, 2026More fossil →

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Physical properties

Hardness: 3-4 (calcite), Color: Greenish-brown, Luster: Vitreous to dull, Crystal structure: Trigonal (calcite replacement)

Formed through the fossilization of ancient sea urchins in marine sedimentary environments during the Paleozoic to Cenozoic eras.

Valued by fossil collectors, educational displays, and scientific research into marine biodiversity.

Many fossilized echinoids are colloquially known as shepherd's crowns or fairy loaves and were historically used as charms.

Identified by radial symmetry and distinctive surface tubercle patterns; found in limestone and chalk deposits globally.

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Likely fossil oyster shell

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

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble

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

Fossil oyster shell

Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)