Crinoid Stem Fragment in Limestone
Crinoid columnal (cf. Platystrinus or similar Paleozoic crinoid) • Body fossil, invertebrate
Geological Period
Mississippian / Carboniferous
Estimated Age
320 to 350 million years
Preservation Type
Permineralization and calcitic replacement
Condition Assessment
Fair to Good, heavily weathered matrix with only minor cross-sections of fossil elements exposed on the surface
Taxonomic Classification
Phylum Echinodermata, Class Crinoidea, Order Cladida
Morphological Description
Small, circular to sub-pentagonal cross-section ossicle showing a central lumen (axial canal). The visible end exhibits radial symmetry characteristic of echinoderm columnals, embedded partially within the weathered rock matrix.
Rock Matrix
Light-colored, weathered argillaceous limestone / biomicrite with minor secondary iron staining
Formation & Location
Paleozoic marine sedimentary sequences globally, such as the Burlington Limestone in the Midwestern United States
Size & Dimensions
Matrix nodule measures approximately 3 to 4 cm across; visible crinoid columnal is roughly 4 to 6 mm in diameter
Value & Rarity
Estimated Market Value
$5 - $15
Auction Estimate
$10 - $25
Rarity Assessment
Common
Scientific Significance
Demonstrates the abundance of crinoids in Paleozoic shallow marine environments, contributing significantly to ancient carbonate rock formation (encrinites)
Preparation Recommendations
Mechanical cleaning using a soft brush or pneumatic engraver if further exposure of internal structures is desired; keep in dry storage
Notable Features
Clear cross-sectional view of the axial canal and typical echinoderm calcite cleavage faces glistening under light