sedimentary
Crinoid Columnal Fossil
Class Crinoidea (Echinodermata); usually calcite replacement (CaCO3)
Hardness: 3 (calcite); Color: Tan, white, or gray; Luster: Dull to earthy; Structure: Disc-shaped or cylindrical with a central hole (lumen) and radial symmetry; specific gravity approx 2.7.
- Hardness
- 3 (calcite)
- Color
- Tan, white, or gray
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (calcite); Color: Tan, white, or gray; Luster: Dull to earthy; Structure: Disc-shaped or cylindrical with a central hole (lumen) and radial symmetry; specific gravity approx 2.7.
Formation & geological history
Formed from the skeletal remains of 'sea lilies' (marine echinoderms). These segments lived during the Paleozoic era (approx. 250-500 million years ago) in shallow, warm sea environments.
Uses & applications
Primarily for geological study, education, and fossil collecting. Historically used as 'Saint Cuthbert's beads' for jewelry or rosaries.
Geological facts
Also known as 'fairy coins' or 'star stones,' crinoids are not plants but animals related to starfish and sea urchins. They were so abundant that they formed entire limestone layers.
Field identification & locations
Identify by looking for the 'cheerio' or button shape with a hole in the center. Common in limestone outcrops in the Midwest USA, UK, and Morocco. Look for them in creek beds and quarries.
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