sedimentary

Fossilized Gastropod in Chert/Limestone

Internal mold of Gastropoda (Class) with CaCO3 or SiO2 mineral formula

Hardness: 3-7 (depending on silicification), Color: Brown to dark grey with lighter fossil suture patterns, Luster: Dull to waxy, Structure: Coiled spiral morphology, Cleavage: None (conchoidal fracture if silica-rich)

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in marine or freshwater environments when sediment filled the shell of a dead snail. Over millions of years (likely Paleozoic or Mesozoic), the sediment lithified while the original shell dissolved or became replaced. Commonly found in riverbeds and limestone outcrops.

Uses & applications

Used primarily as decorative collector specimens or for educational study in paleontology. Highly silicified versions are sometimes polished as 'gem fossils.'

Geological facts

This specimen appears to be a 'steinkern,' a German term meaning 'stone heart,' which is an internal cast of a hollow fossil shell. Millions of years ago, this was a living snail that likely crawled along the sea floor.

Field identification & locations

Identify in the field by looking for 'snail-like' spiral patterns and sutures on water-worn rocks. Found globally in areas with ancient seafloor deposits, particularly the Midwestern United States and European limestone regions.

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