fossil

Fossilized belemnite rostrum (likely)

Belemnitida, a fossil cephalopod guard; exact genus cannot be determined from the image

AI-generated identification · may be incorrect

Elongate, bullet-shaped brown fossil among other fossil fragments. Belemnite guards are commonly calcite, Mohs hardness about 3, with a crystalline structure; the image does not allow reliable assessment of luster or preservation.

Identified October 14, 2026More fossil →

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Physical properties

Formation & geological history

Belemnites were marine squid-like cephalopods that lived from the Late Triassic to the end of the Cretaceous, about 201–66 million years ago. Their internal calcite guards were buried in seafloor sediment and fossilized.

Uses & applications

Primarily collected as fossils and used in education and paleontological displays; not generally an industrial material.

Geological facts

The visible form resembles a belemnite guard, but image-only identification is uncertain. Belemnite fossils are sometimes called “thunderstones” in folklore.

Field identification & locations

Look for a tapered, solid, bullet-like guard, often with a pointed end and a socket at the broader end. They occur in marine sedimentary rocks worldwide, especially Jurassic and Cretaceous deposits; verify the fossil and locality before collecting.