Rock Identifier
Crinoid Stem Fossil (Crinoidea) — fossil
fossil

Crinoid Stem Fossil

Crinoidea

AI-generated identification · may be incorrect

Cylindrical shape, often showing segmented structure or a central canal. Gray to dark gray color. Hardness depends on the replacing mineral, usually calcite or silica (Mohs 3-7). Luster is dull to sub-vitreous. Often found as small, loose, bead-like segments.

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Physical properties

Cylindrical shape, often showing segmented structure or a central canal. Gray to dark gray color. Hardness depends on the replacing mineral, usually calcite or silica (Mohs 3-7). Luster is dull to sub-vitreous. Often found as small, loose, bead-like segments.

Formation & geological history

Marine sedimentary environments from the Paleozoic era (Ordovician to Permian periods, roughly 485 to 252 million years ago). Formed by the fossilization of the stems of crinoids (sea lilies), a type of echinoderm. The skeletal remains, composed of calcium carbonate, were buried in sediment and often replaced by other minerals over time.

Uses & applications

Primarily collected by fossil enthusiasts. Sometimes used in simple jewelry or educational displays. In the past, individual segments were known as 'St. Cuthbert's beads'.

Geological facts

Crinoids are marine animals, not plants, despite their common name 'sea lilies'. They are related to starfish and sea urchins. While mostly extinct, some species still exist in deep oceans today.

Field identification & locations

Identified by their characteristic cylindrical, segmented shape with a central hole or star pattern (though not always visible). Common in many limestone deposits. Often found weathered out of matrix. Look for the distinct radial symmetry or central canal on the ends.

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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

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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