Crinoid calyx with attached stem
Crinoidea indet. cf. cup • Body fossil, invertebrate marine echinoderm
Geological Period
Silurian to Devonian
Estimated Age
419 to 443 million years
Preservation Type
Calcitic replacement and mold/impression in sedimentary matrix
Condition Assessment
Good. The calyx plates are partially weathered and some fine details are obscured, but the overall structure and articulated stem attachment are well preserved.
Taxonomic Classification
Phylum Echinodermata, Class Crinoidea, Order Cladida, Family unknown
Morphological Description
The specimen features a circular to sub-pentagonal crinoid calyx (cup) showing plate sutures and radial symmetry, attached to a segmented columnal stem that tapers downward, displaying characteristic columnal disc stacking and longitudinal striations.
Rock Matrix
Fine-grained argillaceous limestone / calcareous shale containing various microfossils and small skeletal hash fragments
Formation & Location
Silurian-Devonian marine strata globally, notably the Rochester Shale of New York or similar European shelf deposits
Size & Dimensions
Calyx diameter approximately 1.5 cm with a stem length of approximately 2 cm visible in the matrix
Value & Rarity
Estimated Market Value
$50 - $150
Auction Estimate
$75 - $200
Rarity Assessment
Uncommon as an articulated calyx with stem, though isolated crinoid columnals (ossicles) are extremely common.
Scientific Significance
Provides valuable insight into Paleozoic shallow marine benthic ecosystems, crinoid taphonomy, and the sudden burial events that allowed for the preservation of articulated echinoderm parts.
Preparation Recommendations
Gentle mechanical cleaning with an airscribe under low pressure or pin-vise work under a microscope. Store in a stable, low-humidity environment to prevent matrix flaking.
Notable Features
Clear articulation between the dorsal cup and the proximal columnal stem segment, showing the delicate attachment point preserved in relative life position.