fossil

Belemnoit Fossil (Thunderstick)

Belemnitida (Internal rostrum)

AI-generated identification · may be incorrect

Hardness: 3-4 (Calcite), Color: Grey, brown, or translucent yellow, Luster: Vitreous to dull, Shape: Bullet-shaped or conical with a radial crystalline structure in cross-section.

Identified July 6, 2026More fossil →

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Physical properties

Hardness: 3-4 (Calcite), Color: Grey, brown, or translucent yellow, Luster: Vitreous to dull, Shape: Bullet-shaped or conical with a radial crystalline structure in cross-section.

Formation & geological history

Formed from the fossilized internal guard (rostrum) of extinct cephalopods related to modern squid. Predominantly found in marine sedimentary rocks from the Jurassic and Cretaceous periods.

Uses & applications

Educational purposes, scientific research, and collector's items. In folklore, they were once believed to be 'thunderbolts' fallen from the sky.

Geological facts

Belemnites lived in the oceans at the same time as dinosaurs. Unlike modern squid which have a soft 'pen', belemnites had this heavy calcite guard to help balance their bodies while swimming.

Field identification & locations

Commonly found in coastal cliffs or clay pits containing Mesozoic marine sediments. Look for smooth, bullet-like shapes that break to reveal a radiating internal crystal pattern like a starburst.