sedimentary

Fossilized Crinoid Stem

Class Crinoidea (Echinodermata)

Hardness: 3 (calcite composition). Color: Grey, tan, or white. Luster: Dull to vitreous. Structure: Cylindrical or disc-like segments (columnals) often with a central hole (lumen). Cleavage: Rhombohedral (on individual calcite crystals).

Hardness: 3 (calcite composition)
Color: Grey, tan, or white
Luster: Dull to vitreous

Identified January 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the permineralization of marine organisms. These 'sea lilies' were abundant in shallow seas during the Paleozoic era (541 to 252 million years ago), where their segmented stems were buried in calcium-rich sediment.

Uses & applications

Primarily used as educational specimens, biological indicators for dating rock layers, and for mineral collecting. Historically, individual segments were used as beads (sometimes called 'St. Cuthbert's beads').

Geological facts

Crinoids are animals related to starfish and sea urchins, not plants. While most species are extinct, some 'living fossils' still exist in deep oceans today. In the UK, they are famously known as 'star stones' or 'fairy money'.

Field identification & locations

Identify in the field by the distinct 'stacked' appearance of tiny discs or gears. They are extremely common in limestone regions, particularly in the Midwestern United States (like Indiana) and parts of Northern England.

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