Gastropod Internal Mold (Steinkern)

Physical Properties

Hardness: 3-4 (calcitic/silty); Color: Tan to off-white; Luster: Dull, earthy; Structure: Spiral/coiled shape mimicking a snail shell; Cleavage: None (conchoidal to irregular fracture)

Formation & Geological History

Formed when sediment fills a snail shell and hardens, followed by the dissolution of the original shell. Typically found in marine sedimentary layers ranging from the Paleozoic to Cenozoic eras.

Uses & Applications

Educational tools, geological mapping, paleontological study, and amateur fossil collecting.

Geological Facts

Commonly known as a 'steinkern' or 'stone heart'. These represent the negative space inside the creature rather than the actual shell itself.

Field Identification & Locations

Identify by looking for spiral step-like ridges and a lack of shell material. Often found in limestone or shale outcrops near ancient seabeds.

Identified on: 4/28/2026

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