fossil

Fossilized shell or coral fragment

Indeterminate marine mollusk or colonial coral fossil; likely calcite/aragonite replaced by calcite (CaCO₃)

AI-generated identification · may be incorrect

Cream-white, porous, irregularly layered specimen with a dull to slightly pearly luster; hardness about 3 (scratched by steel), low cleavage, and specific gravity near 2.7. The curved growth bands and cavity-like texture suggest a fossil rather than crystalline rock.

Identified September 12, 2026More fossil →

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Physical properties

Formation & geological history

Formed as a marine shell or coral skeleton accumulated in sediment, then mineralized during burial and diagenesis, commonly over thousands to millions of years. Exact age and identity require locality and microscopy.

Uses & applications

Primarily a collectible, educational specimen, or decorative object; carbonate fossils may also be used in small crafts, but this piece is too small and uncertain for construction use.

Geological facts

The visible layered structure may represent shell growth, while the honeycomb-like cavities could indicate coral or dissolution. Acid reaction with dilute hydrochloric acid or vinegar supports a carbonate composition, though it may damage the specimen.

Field identification & locations

Common in marine limestone, beach deposits, and sedimentary exposures worldwide; identify by testing for fizzing, examining symmetry and internal chambers, and checking for mineral replacement. Value is usually $5–$30, or roughly $30–$100 if exceptionally preserved, identified, and locality-documented.