Brachiopod (Lamp Shell)
cf. Mucrospirifer or similar coarsely ribbed Orthida/Spiriferida • Body fossil; Invertebrate (Brachiopoda)
Geological Period
Devonian to Carboniferous (Paleozoic Era)
Estimated Age
320 - 400 million years
Preservation Type
Recrystallization or replacement; possibly calcitic or siliceous replacement of the original shell material.
Condition Assessment
Fair to Good; the specimen is weathered with some marginal chipping and loss of fine surface detail, though the primary ribbing remains visible.
Taxonomic Classification
Phylum: Brachiopoda, Class: Rhynchonellata, Order: Spiriferida or Rhynchonellida
Morphological Description
Convex valve exhibiting strong, concentric growth lines and radiating costae (ribs). The specimen shows a semi-circular profile with a prominent umbo (beak) area, though somewhat abraded.
Rock Matrix
Likely derived from a limestone or calcareous shale matrix; the specimen appears largely freed from the surrounding rock but retains some sedimentary patina.
Formation & Location
Common in formations like the Hungry Hollow Formation (Ontario) or various Silica Shale units in the Midwestern United States (Ohio, Michigan).
Size & Dimensions
Approximately 2-3 cm in width; typical for small to medium-sized Paleozoic brachiopods.
Value & Rarity
Estimated Market Value
$5.00 - $15.00 USD
Auction Estimate
$10.00 - $25.00 USD (typically sold in bulk lots)
Rarity Assessment
Common; marine invertebrates of this type are among the most abundant fossils in Paleozoic marine deposits globally.
Scientific Significance
Brachiopods are vital index fossils for dating Paleozoic strata and provide data on ancient benthic marine environments and water chemistry.
Preparation Recommendations
Minimal preparation required; gentle cleaning with a soft brush. Keep in a dry, stable environment to prevent salt crystallization or surface degradation.
Notable Features
Distinctive 'lampshell' morphology with prominent concentric layers indicating seasonal or episodic growth cycles during the organism's life.