Orthocone Cephalopod (Orthoceras)
Orthoceras cf. regulare • Body fossil, Invertebrate
Geological Period
Ordovician to Silurian Period
Estimated Age
485 to 419 million years
Preservation Type
Replacement and recrystallization; the calcium carbonate shell has likely been replaced by dark calcite or hematite-rich minerals.
Condition Assessment
Good; the specimen has been heavily prepared and polished for commercial sale, which removes original surface detail but highlights internal structures.
Taxonomic Classification
Phylum: Mollusca, Class: Cephalopoda, Subclass: Nautiloidea, Order: Orthocerida, Family: Orthoceratidae
Morphological Description
Long, slender, conical shell with a smooth, dark exterior. Internal anatomy shows evidence of septa (chamber walls) and a siphuncle. The specimen shows a clear longitudinal section through the phragmocone.
Rock Matrix
Typically found in a dark limestone or shale matrix, though the specimen has been fully extracted and polished.
Formation & Location
Commonly found in the Anti-Atlas Mountains of Morocco, specifically the Erfoud region, within the Alnif or Tafilalt formations.
Size & Dimensions
Approximately 10-15 cm in length, which falls within the common juvenile to sub-adult size range for this genus.
Value & Rarity
Estimated Market Value
$15 - $35 USD
Auction Estimate
$10 - $25 USD
Rarity Assessment
Common; these are among the most frequently exported fossils from Morocco and are mass-produced for the gift market.
Scientific Significance
Provides insights into the early evolution of swimming carnivorous mollusks and the paleoecology of shallow marine environments in the Paleozoic era.
Preparation Recommendations
Requires minimal maintenance. Keep away from acidic cleaning agents. Use a soft cloth for dusting and store in a low-humidity environment to prevent oxidation of any iron content.
Notable Features
The high-contrast dark mineralization against the white marble background makes it a distinct decorative piece; characteristic straight-shell morphology is well-preserved.