Brachiopod (Lamp Shell)
cf. Atrypa sp. or Spiriferid indet. (requires closer inspection of the hinge line) • Body fossil; Marine Invertebrate
Geological Period
Devonian to Carboniferous (Paleozoic Era)
Estimated Age
300 - 400 million years
Preservation Type
Recrystallization and replacement; possibly calcified or silicified within the host rock.
Condition Assessment
Fair to Good. One specimen is largely complete but remains partially embedded in the matrix; a second smaller individual is visible adjacent to it.
Taxonomic Classification
Phylum: Brachiopoda, Class: Rhynchonellata, Order: Spiriferida or Atrypida
Morphological Description
Pentamerous or sub-circular bivalved shell displaying convex dorsal and ventral valves. Visible growth lines are present. The primary specimen shows a prominent umbo (beak area) and subtle radiating costae (ribbing).
Rock Matrix
Fine-grained dark grey limestone or calcareous shale, typical of marine sedimentary deposits.
Formation & Location
Commonly found in formations such as the Much Wenlock Limestone (UK) or various Devonian horizons in the Ohio/New York regions (USA).
Size & Dimensions
Approximately 2.5 - 3.5 cm in width, which is consistent with adult specimens of typical Paleozoic brachiopods.
Value & Rarity
Estimated Market Value
$5.00 - $15.00 USD
Auction Estimate
$10.00 - $25.00 USD (as part of a bulk paleontological lot)
Rarity Assessment
Common; Brachiopods are among the most abundant fossils from the Paleozoic era worldwide.
Scientific Significance
Provides evidence of Paleozoic marine benthic communities and helps in biostratigraphic dating of the sedimentary unit.
Preparation Recommendations
Mechanical preparation using a pin-vise or air scribe could further expose the hinge and ornamentation. Store in a dry environment to prevent pyrite decay if present in the matrix.
Notable Features
The specimen features a 'life association' cluster where a smaller brachiopod appears to have settled or fossilized directly adjacent to the larger individual.