Sedimentary

Gastropod Steinkern (Fossilized Snail Cast)

Phylum Mollusca, Class Gastropoda (Commonly CaCO3 or SiO2 after replacement)

AI-generated identification · may be incorrect

Hardness: 3-4 (if calcite) to 7 (if silicified); Color: Beige, tan, or grey; Luster: Dull/Earthy; Structure: Internal mold (steinkern) showing a spiral or helical coil; Cleavage: None (fractures as rock).

Hardness: 3-4 (if calcite) to 7 (if silicified)
Color: Beige, tan, or grey
Luster: Dull/Earthy

Identified March 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when a gastropod shell is filled with sediment (mud or sand), which hardens into rock before the original shell dissolves away. Common in marine deposits from the Paleozoic to Cenozoic eras.

Uses & applications

Used primarily as educational specimens, items for fossil collectors, and sometimes as decorative garden stones if found in large quantities.

Geological facts

The term 'Steinkern' is German for 'stone kernel.' Because snails usually have empty shells after death, they are some of the most common internal mold fossils found in the world.

Field identification & locations

Identify in the field by the distinctive coiled 'cinnamon roll' shape and lack of actual shell surface detail. Commonly found in limestone quarries, road cuts, and dry creek beds.