fossil

Fossiliferous Limestone (Crinoid stem fragment)

Crinoidea (Phylum Echinodermata) in Calcite matrix

AI-generated identification · may be incorrect

Commonly gray or tan with white circular markings. Hardness: 3 (Mohs scale), Luster: Dull to earthy, Cleavage: None (rhombohedral in crystal form), Density: 2.71 g/cm³.

Identified July 13, 2026More fossil →

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Physical properties

Commonly gray or tan with white circular markings. Hardness: 3 (Mohs scale), Luster: Dull to earthy, Cleavage: None (rhombohedral in crystal form), Density: 2.71 g/cm³.

Formation & geological history

Formed in warm, shallow marine environments where organic debris accumulated on the seafloor. Typical age ranges from the Ordovician to the Carboniferous periods (approx. 300-480 million years ago).

Uses & applications

Used primarily as decorative stones, educational specimens for paleontology, and in the production of lime or cement in industry.

Geological facts

Crinoids are known as 'sea lilies' but are actually animals related to starfish. The 'Cheerios' shaped markings on the rock are cross-sections of their calcified skeletal stems.

Field identification & locations

Identified by tiny white circles or screws-like cylinders embedded in a softer matrix. Found worldwide in ancient seabed deposits, particularly in the Midwestern United States and the UK.