Fossilized Gastropod Steinkern in Flint Matrix
Gastropoda indet. (likely internal mold of a nerineid or similar Cretaceous snail) • Internal mold (steinkern) body fossil of an invertebrate
Geological Period
Cretaceous
Estimated Age
66 to 145 million years
Preservation Type
Silicification and internal mold (steinkern) preservation where original aragonitic shell material has been replaced by silica/chalcedony.
Condition Assessment
Fair to Good; the specimen is heavily weathered and waterworn with partial exposure of the internal whorls, lacking fine external ornamentation due to the nature of steinkern preservation.
Taxonomic Classification
Phylum Mollusca, Class Gastropoda
Morphological Description
The specimen exhibits a weathered, rounded nodular morphology with visible internal whorls and spiral structure preserved as a lighter-toned calcareous or silicified steinkern embedded within a dense greyish chert/flint matrix.
Rock Matrix
Chert/Flint nodule with a weathered outer cortex, indicative of replacement processes in a chalk or limestone host rock.
Formation & Location
Upper Cretaceous chalk deposits, commonly found in regions such as the chalk downlands of Western Europe, the Gulf Coast of the United States, or the Midwest.
Size & Dimensions
Approximately 5 cm to 7 cm in maximum length, falling well within the typical size range for medium-sized Mesozoic marine gastropods.
Value & Rarity
Estimated Market Value
10 USD to 30 USD
Auction Estimate
15 USD to 45 USD
Rarity Assessment
Common; flint-replaced fossil steinkerns are frequently encountered in cretaceous chalk formations globally.
Scientific Significance
Demonstrates the tapinonomic process of silicification in carbonate environments and provides evidence of shallow marine benthic communities during the Cretaceous period.
Preparation Recommendations
No intensive preparation is strictly required as the specimen is naturally weathered; gentle cleaning with water and a soft brush to remove loose surface dirt is sufficient. Store in a dry environment.
Notable Features
Clear spiral internal mold configuration visible through differential weathering of the softer interior versus the durable surrounding flint matrix.