sedimentary
Gastropod Internal Mold (Steinkern)
Class Gastropoda fossil mold (Phylum Mollusca)
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)
- Hardness
- 3-4 (calcitic/silty)
- Color
- Tan to off-white
- Luster
- Dull, earthy
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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.
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