fossil

Fossilized bivalve shell

Molluscan bivalve fossil; shell originally composed of calcium carbonate (aragonite/calcite, CaCO₃)

AI-generated identification · may be incorrect

Hardness about 3–4 Mohs; off-white to tan, with ribbed shell texture and brown mineral staining or matrix. Pearly to dull luster; original shell has layered structure, though fossilization may replace it with calcite or silica.

Identified August 17, 2026More fossil →

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Physical properties

Formation & geological history

A marine clam or similar bivalve was buried in sediment, then mineralized during diagenesis; its exact geological age cannot be determined from the image. Such fossils range from Paleozoic to modern deposits and commonly occur in limestone, shale, or unconsolidated coastal sediments.

Uses & applications

Primarily a teaching, display, and collecting specimen; complete or unusually old examples may be sold as natural-history curiosities rather than used industrially.

Geological facts

The visible shell curvature and concentric growth features are consistent with a bivalve, but species-level identification requires the hinge, shell interior, and both valves.

Field identification & locations

Look for bilateral paired valves, a hinge line, growth rings, and carbonate fizz with dilute acid (test only an inconspicuous spot). Commonly found in marine sedimentary rocks and coastal fossil beds.