Oyster Shell Fragment
cf. Gryphaea arcuata (or similar oyster species native to the region) • Body fossil, invertebrate
Geological Period
Jurassic to Cretaceous
Estimated Age
160 to 90 million years
Preservation Type
Calcitic replacement and natural internal mold (steinkern)
Condition Assessment
Fair; represents a partial valve or internal mold with wear along the margins, but structurally stable
Taxonomic Classification
Phylum Mollusca, Class Bivalvia, Order Ostreida, Family Ostreidae, Genus cf. Gryphaea or Exogyra
Morphological Description
Curved, cup-shaped internal mold and partial shell fragment showing smooth interior contour and a thick calcareous outer layer with faint concentric growth lines.
Rock Matrix
Marly limestone and argillaceous matrix typical of coastal cliff formations
Formation & Location
Vaches Noires cliffs (Falaises des Vaches Noires), Normandy, France
Size & Dimensions
Approximately 1.5 cm to 2 cm in diameter, consistent with juvenile or fragmented specimens from this formation
Value & Rarity
Estimated Market Value
5 to 15 USD
Auction Estimate
Not typically traded at auction; primarily a field souvenir or educational specimen
Rarity Assessment
Common
Scientific Significance
Demonstrates shallow marine depositional environments of the Mesozoic era in coastal Normandy, contributing to paleoecological reconstructions of ancient shelf seas
Preparation Recommendations
Gentle mechanical cleaning with a soft brush to remove loose matrix; store in a dry environment
Notable Features
Good comparative scale against the adjacent 2-euro coin, clearly displaying the deep cup shape characteristic of attached benthic bivalves
Notes
falaises des Vaches Noires