Crinoid Ossicle (Columnal)
Incertae sedis; most likely a species of Platycrinites or general Paleozoic crinoid • Body fossil; Invertebrate (Echinoderm)
Geological Period
Mississippian sub-period of the Carboniferous Period
Estimated Age
325 to 350 million years
Preservation Type
Mineral replacement (typically calcium carbonate/calcite) with likely iron oxide or hematite staining, giving it a dark reddish-brown hue.
Condition Assessment
Good. It is a complete, single ossicle. The edges and surface show significant water-wearing or sedimentary abrasion, softening the original radial ornament (crenularium).
Taxonomic Classification
Phylum: Echinodermata; Class: Crinoidea; Order: Not determined (cf. Millericrinida or similar); Family: Various; Genus: cf. Platycrinites
Morphological Description
Disc-shaped stem segment with circular symmetry. Features a central lumen (perforation) for the nutrient canal. The articular surface appears weathered but typical of a columnal stack segment.
Rock Matrix
The fossil appears free of matrix; however, it likely originated from a crinoidal limestone or shale with high iron content.
Formation & Location
Common in the Burlington Limestone (USA, Iowa/Missouri/Illinois) or similar Carboniferous marine deposits globally (UK, Russia, North America).
Size & Dimensions
Approximately 2 to 3 cm in diameter, which is a standard to large-sized ossicle for Carboniferous taxa.
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $30 USD (usually sold in lots rather than individually)
Rarity Assessment
Common. Crinoid stem fragments are among the most abundant Paleozoic fossils found worldwide.
Scientific Significance
Represents the remnants of Paleozoic 'sea lily' gardens. Significant for understanding marine biodiversity and the heavy calcification of life during the Carboniferous.
Preparation Recommendations
Requires no further prep. Keep dry and avoid acidic cleaners which could dissolve the calcite structure. Display in a standard specimen tray.
Notable Features
Distinctively dark coloration suggesting a high iron content in the burial environment; the central hole is exceptionally well-defined, often leading these to be used historically as 'bead stones' or 'St. Cuthbert's beads'.