Fossil Sea Urchin Internal Mold (Echinoid Flint Cast / 'Witch's Stone')
cf. Echinocorys scutata or cf. Micraster sp. (internal steinkern preserving ambulacral/gonopore voids) • Body fossil / Internal mold (steinkern) - Invertebrate (Echinoderm)
Geological Period
Late Cretaceous
Estimated Age
Approx. 66 - 90 million years
Preservation Type
Silicification / Flint steinkern (internal mold produced by silica replacement inside the original calcite test, which later dissolved away)
Condition Assessment
Fair - Weathered and rolled beach/gravel pebble specimen with eroded fine surface details, but distinct anatomical pore impressions remaining
Taxonomic Classification
Phylum: Echinodermata, Class: Echinoidea, Order: Spatangoida or Holectypoida, Family: Micrasteridae / Galeritidae
Morphological Description
Rounded, ovate flint/chert steinkern featuring smooth, weathered surfaces with prominent ovate cavities corresponding to internal anatomical features such as the apical system, gonopores, or ambulacral pathways.
Rock Matrix
Chert / Flint nodule derived from Cretaceous Chalk beds
Formation & Location
Commonly found in the Chalk Group of Western Europe (e.g., Southern England beaches/coasts, Northern France, Denmark) or derived glacial gravels
Size & Dimensions
Approximately 4 - 6 cm in length, typical for medium-sized Cretaceous echinoids
Value & Rarity
Estimated Market Value
$5 - $15 USD
Auction Estimate
$10 - $20 USD
Rarity Assessment
Common (frequently found along UK and European coastline beaches and chalk gravels)
Scientific Significance
Demonstrates silica replacement dynamics in Cretaceous marine chalk environments and provides insight into benthic echinoid anatomy through internal cast preservation.
Preparation Recommendations
No invasive chemical or mechanical prep needed. Clean with water and soft brush; store in a dry environment to prevent mechanical chipping.
Notable Features
Distinctive pair of large anatomical voids giving the specimen a mask-like or face-like appearance, a classic feature of eroded echinoid steinkerns often historically referred to as hagstones or witch stones.