Fossilized Brachiopod Assemblage in Limestone Matrix
Brachiopod sp. cf. Spirifer or related articulate brachiopod taxa • Body fossil and mold/cast preservation, invertebrate marine organism
Geological Period
Devonian to Carboniferous
Estimated Age
300 to 400 million years old
Preservation Type
Calcitic replacement and natural molds within a sedimentary matrix
Condition Assessment
Good condition, featuring partial shell exposure and natural weathering, with some surface abrasion but clear internal structural details
Taxonomic Classification
Phylum Brachiopoda, Class Rhynchonellata, Order Strophomenida
Morphological Description
Multiple articulate brachiopod shells embedded within the rock, showing prominent radiating costae (ribs), distinct hinge lines, and fan-shaped symmetrical valves with visible growth lines.
Rock Matrix
Buff-colored crinoidal limestone containing secondary calcite and weathered fossil hash
Formation & Location
Midwest United States (such as the Silica Shale or Jeffersonville Limestone formations)
Size & Dimensions
Approximately 12 cm in length and 6 cm in maximum width, typical of medium-sized Paleozoic brachiopods
Value & Rarity
Estimated Market Value
$15 - $45
Auction Estimate
$20 - $50
Rarity Assessment
Common, widely distributed across numerous Paleozoic marine deposits globally
Scientific Significance
Provides valuable insight into Paleozoic shallow marine benthic communities, localized bioclastic accumulation, and benthic ecosystem recovery following mass extinction events
Preparation Recommendations
Light mechanical cleaning with a soft brush and gentle air abrasion if desired, stored in a dry environment with stable humidity
Notable Features
Multiple overlapping brachiopod specimens exposed in cross-section and flat view, showcasing varying preservation states within a dense bioclastic limestone matrix