fossil

Crinoid Stem Fossil in Chert

Crinoid columnal ossicles (phylum Echinodermata) embedded in microcrystalline quartz (chert)

Hardness: 7 (due to the chert matrix); Color: Dark gray, brownish-gray with white, circular ring-like fossil cross-sections; Luster: Vitreous to dull; Crystal structure: Microcrystalline (quartz) with calcitic fossil remnants

Hardness: 7 (due to the chert matrix)
Luster: Vitreous to dull

Identified August 4, 2026More fossil →

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Physical properties

Formation & geological history

Formed in ancient shallow marine environments during the Paleozoic era (often Mississippian or Devonian, roughly 300-400 million years ago), where skeletal fragments of crinoids accumulated in sediment that was later silicified into chert.

Uses & applications

Collectible specimen, educational tool, lapidary study, and occasionally used in amateur fossil and rock collecting displays.

Geological facts

Crinoids are commonly known as 'sea lilies' because of their plant-like appearance, though they are actually marine animals related to starfish and sea urchins. In popular folklore, fossil crinoid stems are sometimes called 'St. Cuthbert's beads' or Indian bead stones.

Field identification & locations

Easily identified in the field by the distinctive round or pentagonal button-like rings with a central hole (often resembling tiny wagon wheels or screws). Commonly found in gravel beds, limestone formations, and stream gravels where chert nodules weather out.

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

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Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Crinoid Stem Fossils (Indian Beads / St. Cuthbert's Beads)

Crinoid columnal ossicles (phylum Echinodermata)

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Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

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Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary