sedimentary
Crinoid Stem Fossil
Class Crinoidea (Phylum Echinodermata), often preserved in Limestone or Calcite (CaCO3)
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 More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
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.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary