fossil
Crinoid Stem Fossil in Limestone
Crinoidea (class) in Calcium Carbonate (CaCO3) matrix
Hardness: 3-4 (matrix); Color: Grey, brownish-grey, or tan; Luster: Dull to earthy; Feature: Disc-like or cylindrical segmented structures visible on the surface.
- Hardness
- 3-4 (matrix)
- Color
- Grey, brownish-grey, or tan
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (matrix); Color: Grey, brownish-grey, or tan; Luster: Dull to earthy; Feature: Disc-like or cylindrical segmented structures visible on the surface.
Formation & geological history
Formed from the calcified remains of marine echinoderms known as sea lilies. These typically date back to the Paleozoic era (approx. 250-500 million years ago) and were preserved in seabed sediments that turned into limestone.
Uses & applications
Educational specimens, fossil collecting, and occasionally used in jewelry once cut and polished (known as Petoskey-like fossils in some regions).
Geological facts
Crinoids are known as 'living fossils' because their descendants still live in deep oceans today. During the Mississippian Period, they were so abundant that they formed thick layers of rock consisting almost entirely of their skeletal fragments.
Field identification & locations
Look for the characteristic 'stacked coin' appearance of the stem segments. These are very commonly found in limestone creek beds, quarries, and road cuts across the Midwest United States and the UK.
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