Rock Identifier
Belemnite Fossil (Thunderbolt Stone) (Belemnitida rostrum (predominantly Calcite, CaCO3)) — fossil
fossil

Belemnite Fossil (Thunderbolt Stone)

Belemnitida rostrum (predominantly Calcite, CaCO3)

AI-generated identification · may be incorrect

Hardness 3 Mohs; bullet-shaped/cigar-shaped cylinder with radial fibrous calcite structure; vitreous to dull luster; amber to brownish-gray color.

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Physical properties

Hardness 3 Mohs; bullet-shaped/cigar-shaped cylinder with radial fibrous calcite structure; vitreous to dull luster; amber to brownish-gray color.

Formation & geological history

Internal skeleton (rostrum) of extinct squid-like cephalopods from the Mesozoic Era (Jurassic to Cretaceous, ~200–66 Ma), commonly preserved in marine sedimentary rocks.

Uses & applications

Prized as paleontological specimens, educational display items, and occasionally polished for novelty jewelry or talismans.

Geological facts

Historically called 'devil's fingers' or 'thunderbolts' in European and Russian folklore, belemnite rostra provided counterweights to stabilize the living cephalopod while swimming.

Field identification & locations

Identified by its distinctive tapered bullet shape and radial fibrous calcite structure visible in cross-section; very common in Mesozoic marine sediments around Bashkortostan/Ural foothills.

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Likely fossil oyster shell

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Crinoid Stem Fossil in Matrix (Phylum Echinodermata, Class Crinoidea) — fossil

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
Porous limestone pebble (Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image) — sedimentary

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

sedimentary
Weathered fossil bone fragment (identification uncertain) (Fossilized bone; exact taxon and mineral composition cannot be determined from the image) — fossil

Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

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