sedimentary
Crinoid Stem Fossil
Class Crinoidea (Sea Lilies)
Hardness: 3 (Calcite); Color: Gray, tan, or white; Luster: Dull to earthy; Crystal structure: Hexagonal/Trigonal (individual ossicles); Appearance: Segmented, cylindrical, often with a central hole.
- Hardness
- 3 (Calcite)
- Color
- Gray, tan, or white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (Calcite); Color: Gray, tan, or white; Luster: Dull to earthy; Crystal structure: Hexagonal/Trigonal (individual ossicles); Appearance: Segmented, cylindrical, often with a central hole.
Formation & geological history
Formed during the Paleozoic era (approx. 250-500 million years ago) in shallow marine environments. Fossilization occurs when the calcium carbonate skeletons are buried in lime mud which eventually hardens into limestone.
Uses & applications
Primarily for education, scientific study, and fossil collecting. Historically used for making bead jewelry and buttons.
Geological facts
Crinoids are actually animals (echinoderms) related to starfish and sea urchins, not plants. They are often called 'Sea Lilies' because of their flower-like appearance. In some cultures, fossilized segments are called 'fairy stones' or 'St. Cuthbert's beads'.
Field identification & locations
Identified by cylindrical segments or 'chewed' looking columnals in sedimentary rock. Commonly found in limestone outcrops, riverbeds, and quarries across the Midwestern US and UK.
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