Brachiopod external mold
Brachiopod indet. cf. Platystrophia or similar rhynchonelliform genus • Invertebrate body fossil (mold / impression)
Geological Period
Ordovician to Devonian (Paleozoic Era)
Estimated Age
485 to 359 million years
Preservation Type
External mold / natural impression in sedimentary rock
Condition Assessment
Good condition; a crisp and well-defined natural mold showing clear concentric ornamentation, though preserved as a single solitary impression rather than a full articulated shell
Taxonomic Classification
Phylum: Brachiopoda, Class: Articulata, Order: Orthida or Spiriferida, Family: Various, Genus: undetermined
Morphological Description
Small, sub-triangular to rounded outer shell impression displaying distinct, concentric growth lines radiating from a hinge or apex area. The concavity clearly preserves the fine micro-ornamentation of the exterior valve surface.
Rock Matrix
Fine-grained calcareous siltstone or argillaceous limestone matrix
Formation & Location
Paleozoic marine sedimentary formations globally, such as the Cincinnatian Group in North America or similar shallow marine shales and limestones
Size & Dimensions
Approximately 10 mm to 12 mm across, consistent with small juvenile or miniature adult brachiopod specimens of the Paleozoic
Value & Rarity
Estimated Market Value
5 to 15 USD
Auction Estimate
10 to 25 USD
Rarity Assessment
Common
Scientific Significance
Provides evidence of ancient shallow marine shelf environments and benthic invertebrate community structures during the Paleozoic era
Preparation Recommendations
No intensive preparation required; can be cleaned gently with a soft brush and water. Store in a dry, stable environment.
Notable Features
Exceptionally sharp and clean external mold retaining delicate concentric growth ridges with high fidelity.