Fossilized Echinoid (Sea Urchin) Steinkern
Echinoidea indet. cf. Echinocorys • Internal mold (steinkern), invertebrate body fossil
Geological Period
Cretaceous
Estimated Age
66 to 145 million years
Preservation Type
Natural internal mold (steinkern) with complete calcitic test dissolution and complete matrix infilling
Condition Assessment
Good condition; exhibits moderate weathering and smoothing of surface details due to natural exposure or rolling, but maintains its complete three-dimensional shape
Taxonomic Classification
Phylum Echinodermata, Class Echinoidea, Order Irregularia
Morphological Description
Rounded to slightly pentagonal internal cast displaying smooth weathered surfaces with faint traces of ambulacral grooves radiating from the apex. The apical disc area is obscured by matrix and weathering, and the oral surface is largely unexposed in the provided view.
Rock Matrix
Silicified limestone or chalk matrix with iron oxide staining (patina)
Formation & Location
Upper Cretaceous chalk deposits, commonly found in Western Europe (e.g., UK, France) or the chalk formations of North America
Size & Dimensions
Approximately 5 to 7 cm in diameter, falling within the average size range for irregular echinoids of this type
Value & Rarity
Estimated Market Value
15 to 35 USD
Auction Estimate
20 to 50 USD
Rarity Assessment
Common
Scientific Significance
Provides insight into Cretaceous marine benthic ecosystems and soft-sediment burrowing behaviors of irregular echinoids
Preparation Recommendations
No aggressive preparation needed. Gentle washing with water and a soft brush to remove surface debris is sufficient. Store in a stable, dry environment.
Notable Features
Pleasing golden-brown iron oxide patina and smooth, tactile preservation typical of flint-nodule or chalk-hosted steinkerns