Fossil Brachiopod Shell
cf. Spirifer sp. • Body fossil, invertebrate marine organism
Geological Period
Devonian
Estimated Age
359 to 419 million years
Preservation Type
Original calcite shell material preserved via permineralization and minor replacement with microcrystalline quartz in a sedimentary matrix
Condition Assessment
Good condition. Moderately complete single valve or articulated fragment with some breakage along the lateral margins and the beak area, but preserving clear surface ornamentation.
Taxonomic Classification
Phylum Brachiopoda, Class Rhynchonellata, Order Spiriferida, Family Spiriferidae
Morphological Description
The specimen exhibits prominent, rounded radial costae (ribs) radiating from the umbo toward the margin. The shell displays a biconvex profile with a distinct fold and sulcus visible along the commissure. The surface shows fine concentric growth lines intersecting the prominent costae, creating a textured reticulate appearance under magnification.
Rock Matrix
Light-colored argillaceous limestone / calcareous mudstone
Formation & Location
Widely distributed globally; common in the Hamilton Group of New York or equivalent Devonian strata in North America and Europe
Size & Dimensions
Approximately 4 cm in width, 3 cm in length, and 2.5 cm in thickness, falling within the standard adult size range for the taxon
Value & Rarity
Estimated Market Value
$10 - $25
Auction Estimate
$5 - $15
Rarity Assessment
Common
Scientific Significance
Provides valuable data for paleoecological reconstructions of shallow marine benthic environments during the Paleozoic era, contributing to studies of evolutionary lineages and mass extinction events
Preparation Recommendations
Mechanical cleaning using a fine needle or air abrasive pen to remove excess matrix. Store in a stable, dry environment away from high humidity to prevent matrix degradation.
Notable Features
Well-defined radial costae and clear growth lines providing sharp textural contrast across the dorsal or ventral valve surface