Belemnoit Fossil (Sea Squid Fossil)

Physical Properties

Hardness: 3 (calcite composition), Color: Grey, brown, or yellowish, Luster: Silky to glassy, Structure: Tapered bullet shape with radiating internal crystal structure

Formation & Geological History

Formed from the internal calcified shell (rostrum) of extinct cephalopods that lived during the Jurassic and Cretaceous periods (approx. 200 to 66 million years ago). Found in marine sedimentary layers.

Uses & Applications

Primarily used for educational fossils collections, geological research, and sometimes polished for use as charms or jewelry.

Geological Facts

Commonly known as 'thunderbolts' in ancient folklore, people once believed these fell from the sky during storms. They were the internal skeleton of creatures related to modern squids and cuttlefish.

Field Identification & Locations

Identify by the 'bullet' shape with a circular cross-section. Often found in chalk and limestone cliffs or marine clay deposits. Look for the distinctive radial pattern when looking at a broken end.

Identified on: 5/18/2026

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