fossil

Fossilized Gastropod Internal Mold

Gastropoda (Steinkern fossil)

Hardness: 3 to 7 Mohs depending on host rock matrix (typically fine-grained sandstone, siltstone, or limestone). Color: Earthy brown to tan with visible spiral coiling imprint. Luster: Dull, earthy. Structure: Spiral or helical mold of a prehistoric snail shell.

Color: Earthy brown to tan with visible spiral coiling imprint
Luster: Dull, earthy

Identified July 24, 2026More fossil →

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Physical properties

Formation & geological history

Formed during sedimentary processes when sediment filled the internal cavity of a dead gastropod shell. Over geological time, the sediment hardened into stone, and the original shell often dissolved away, leaving an internal mold (steinkern). Commonly found in marine sedimentary layers worldwide.

Uses & applications

Geological collection, educational tools, fossil study, and decorative specimens.

Geological facts

Internal molds of gastropods are known as 'steinkerns', a German word meaning 'stone core'. They preserve the precise shape of the inner shell chambers even when the actual shell material has completely weathered away.

Field identification & locations

Identified by the distinct coiled spiral pattern characteristic of sea snails or terrestrial gastropods preserved in fine sedimentary stone. Found in riverbeds, limestone quarries, and coastal bluffs.

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