Fossiliferous Sedimentary Matrix / Shell Bed Fragment
Invertebrate indet. (requires closer inspection for specific taxa identification) • Body fossils (invertebrate accumulation) in a calcareous sedimentary matrix
Geological Period
Likely Devonian to Cretaceous depending on provenance
Estimated Age
Approx. 66 to 400 million years
Preservation Type
Recrystallization and impression; fossils are integrated into the cemented matrix
Condition Assessment
Fair; the specimen is a highly weathered fragment with high degree of fragmentation and lack of diagnostic articulation
Taxonomic Classification
Phylum: Mollusca/Brachiopoda; Class: Bivalvia or Articulata (Indeterminate fragment)
Morphological Description
Small, fragmented shell impressions and calcified debris visible in a coarse, granular matrix. Shows evidence of bioclastic accumulation with irregular surface textures and small vugs.
Rock Matrix
Calcareous sandstone or biomicritic limestone with quartz grains and possible calcite cementation
Formation & Location
Common in marine formations such as those in the Midwest US (Cincinnati Arch) or the Jurassic Coast of the UK
Size & Dimensions
Approximately 4-6 cm in width (typical hand-sample size for field collection)
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $25 USD (likely as part of a bulk lot)
Rarity Assessment
Common; representative of standard fossiliferous marine strata
Scientific Significance
Represents a high-energy depositional environment or a death assemblage (thanatocoenosis) documenting local marine biodiversity
Preparation Recommendations
Mechanical cleaning with a soft brush; avoid acid baths as they may dissolve the calcareous shell fragments alongside the matrix
Notable Features
The specimen serves as a 'micro-ecosystem' display showing the Density of marine life in a single block of ancient seabed