sedimentary

Crinoid Stem Fossil

Class Crinoidea (Phylum Echinodermata), often preserved in Limestone or Calcite (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (calcite); Color: Tan, gray, or white; Luster: Dull to earthy; Structure: Segmented cylindrical columns (columnals) with a central hole (lumen); Specific Gravity: 2.7

Hardness: 3 (calcite)
Color: Tan, gray, or white
Luster: Dull to earthy

Identified March 18, 2026More sedimentary →

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Physical properties

Hardness: 3 (calcite); Color: Tan, gray, or white; Luster: Dull to earthy; Structure: Segmented cylindrical columns (columnals) with a central hole (lumen); Specific Gravity: 2.7

Formation & geological history

Formed through the fossilization of marine organisms' skeletal remains in shallow sea environments. Most specimens range from the Ordovician to the Permian periods (approx. 485 to 252 million years ago).

Uses & applications

Primarily used as educational specimens, for fossil collecting, and occasionally as decorative beads or architectural limestone accents.

Geological facts

Crinoids are known as 'sea lilies' but are actually animals related to starfish and sea urchins. They were so abundant during the Mississippian subperiod that it is often called the 'Age of Crinoids.'

Field identification & locations

Identify by looking for stacked, ring-like segments that look like screws or bolts; found in limestone outcrops, stream beds in the Midwest US (Kentucky, Indiana), and shoreline deposits. Check for the central circular or star-shaped hole.