Fossil Sea Urchin (Echinoid)
cf. Heteraster or similar spatangoid echinoid • Body fossil, invertebrate
Geological Period
Cretaceous
Estimated Age
66 to 145 million years old
Preservation Type
Silicification and complete calcitic replacement/permineralization within the test structure
Condition Assessment
Good condition; the test is largely complete with clear ambulacral patterns, though displaying some surface weathering, pitting, and localized matrix encrustation or damage on the lower right quadrant
Taxonomic Classification
Phylum Echinodermata, Class Echinoidea, Order Spatangoida
Morphological Description
Heart-shaped to rounded irregular echinoid test displaying a distinct five-rayed petaloid ambulacral system on the dorsal surface, with flush or slightly sunken petals radiating from a central apical disc area. Smooth weathered surface showing fine plate sutures and tubercle scars.
Rock Matrix
Light tan to brownish fossiliferous limestone with minor iron oxide staining and secondary quartz or calcite infill
Formation & Location
Commonly found in Cretaceous chalk and limestone formations globally, such as the Austin Chalk in Texas, USA, or deposits in Morocco and Western Europe
Size & Dimensions
Approximately 5 to 7 cm in diameter, matching the typical average size range for this taxonomic group
Value & Rarity
Estimated Market Value
$25 - $75 USD
Auction Estimate
$20 - $50 USD
Rarity Assessment
Common
Scientific Significance
Provides valuable data on Cretaceous shallow marine paleoenvironments, benthic ecology, and the evolutionary history of irregular sea urchins that adapted to burrowing lifestyles
Preparation Recommendations
Gentle mechanical cleaning with a soft brush and water to remove loose debris; chemical preparation should be avoided to prevent damage to the mineralized test. Store in a stable, dry environment.
Notable Features
Well-defined petaloid pores and clear bilateral symmetry characteristic of irregular heart urchins, highlighted by natural color variations in the matrix and fossil shell