Rock Identifier
Fossilized Crinoid Stem in Limestone (Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix) — fossil
fossil

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

Hardness: 3-4 (matrix), Color: Light gray to tan pebble with a circular brown fossil inclusion, Luster: Dull/Earthy, Structure: Pentapartite or circular symmetry in the fossil stem segment

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Physical properties

Hardness: 3-4 (matrix), Color: Light gray to tan pebble with a circular brown fossil inclusion, Luster: Dull/Earthy, Structure: Pentapartite or circular symmetry in the fossil stem segment

Formation & geological history

Formed during the Paleozoic era (approx. 250-500 million years ago) in shallow marine environments where skeletal fragments of sea lilies were buried and lithified in calcium-rich mud.

Uses & applications

Educational specimens, decorative river stones, jewelry (when polished), and geological study.

Geological facts

Crinoids are known as 'sea lilies' but are actually echinoderms related to starfish. The circular feature in this stone is a cross-section of a columnar segment of the animal's stem.

Field identification & locations

Commonly found in limestone river beds or beaches. Identify by looking for distinct geometric or circular patterns ('buttons' or 'star shapes') embedded in a softer sedimentary matrix.

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