Brachiopod Fossil
Rhynchonella cf. acuminata • Body fossil, invertebrate
Geological Period
Ordovician to Devonian (likely Paleozoic era)
Estimated Age
350 to 450 million years
Preservation Type
Permineralization and calcitic replacement
Condition Assessment
Good, showing a partially exposed shell with some wear on the margins but clear diagnostic plications and structural integrity
Taxonomic Classification
Phylum Brachiopoda, Class Articulata, Order Rhynchonellida, Family Rhynchonellidae
Morphological Description
Exhibits prominent radial ribs or plications radiating from the umbo toward the anterior margin, with a strongly biconvex shell profile and a distinct fold and sulcus visible along the commissure.
Rock Matrix
Grey argillaceous limestone with minor secondary calcite crystal infill
Formation & Location
Found globally in shallow marine Paleozoic sedimentary formations such as the Finis Shale or similar limestone-shale sequences in North America and Europe
Size & Dimensions
Approximately 3 cm in maximum width, typical for medium-sized Paleozoic rhynchonellid brachiopods
Value & Rarity
Estimated Market Value
15 - 45 USD
Auction Estimate
20 - 50 USD
Rarity Assessment
Common, widely distributed across various Paleozoic marine deposits globally
Scientific Significance
Provides important biostratigraphic markers for Paleozoic marine environments and helps reconstruct ancient benthic shallow-water ecosystems
Preparation Recommendations
Mechanical cleaning with fine pin vices or an air abrasive unit using delicate parameters to clear excess matrix from between plications; store in a dry, stable environment
Notable Features
Well-defined prominent plications and sharp commissure edge showing clear asymmetric growth lines