fossil

Orthoceras Fossil

Orthoceras regulare (Class Cephalopoda, Order Orthocerida)

Hardness: 3-4 (calcite-based); Color: white to light grey fossil chambers against a dark grey or black limestone matrix; Luster: Vitreous to dull (polished in this specimen); Crystal structure: Traces of aragonite/calcite replacement.

Hardness: 3-4 (calcite-based)
Luster: Vitreous to dull (polished in this specimen)

Identified July 5, 2026More fossil →

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Physical properties

Formation & geological history

Formed through the permineralization of ancient nautiloid shells in marine sediments. These specimens typically date back to the Devonian Period, approximately 350 to 400 million years ago, primarily in what is now the Sahara Desert in Morocco.

Uses & applications

Commonly used for ornamental purposes, paperweights, jewelry (cabochons), and as educational specimens for fossil collectors.

Geological facts

Orthoceras were ancestors to the modern squid and lived in a shell divided into internal chambers. As the animal grew, it would move forward into a new chamber and seal off the old ones with a wall called a septa.

Field identification & locations

Identify by the distinctive cone-shaped, multi-chambered internal structure (siphuncle) visible in cross-section. Large deposits are found in the Erfoud region of Morocco. They are widely available and perfect for beginner collectors.

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