sedimentary
Crinoid Stalk in Limestone
Crinoid fossil in Biomicrite (Limestone)
Hardness: 3-4 (calcite), Color: Light gray to tan matrix with darker fossil inclusion, Luster: Dull/Earthy matrix, Silky to pearly fossil section, Structure: Crystalline matrix with disk-shaped or tubular segments.
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Physical properties
Hardness: 3-4 (calcite), Color: Light gray to tan matrix with darker fossil inclusion, Luster: Dull/Earthy matrix, Silky to pearly fossil section, Structure: Crystalline matrix with disk-shaped or tubular segments.
Formation & geological history
Formed during the Paleozoic era (approx. 250-500 million years ago) in shallow marine environments. The rock is a limestone formed from compressed marine sediment and skeletal fragments.
Uses & applications
Informational/Educational specimens, geological hobbyist collecting, and indicators of ancient marine environments in tectonic studies.
Geological facts
Crinoids are known as 'sea lilies' but are actually animals related to starfish and sea urchins. They were so abundant that entire rock layers consist almost exclusively of their skeletal remains.
Field identification & locations
Identify by looking for 'Cheerios' or circular patterns with a central hole (lumen) often embedded in gray rock. Found globally in limestone outcrops, road cuts, or riverbeds in the Midwest US and UK.
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