fossil

Fossil bivalve shell

Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features

AI-generated identification · may be incorrect

Calcitic shell, brown to gray with strong radial ribs and concentric growth lines; Mohs hardness about 3, vitreous to pearly luster, layered crystalline structure, and commonly indistinct cleavage. The specimen appears polished or naturally smoothed rather than a rock matrix.

Identified August 7, 2026More fossil →

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Physical properties

Formation & geological history

A marine bivalve shell formed biologically from calcium carbonate, later buried and potentially mineralized during fossilization; age cannot be determined from the image. Comparable shells occur in Cenozoic marine sediments and modern beaches worldwide.

Uses & applications

Primarily a collectible, teaching specimen, or decorative object; fossil shell material is not generally used industrially or as gemstone material.

Geological facts

Radial ribs strengthened the shell against waves and predators, while growth lines record seasonal or environmental changes. Brown coloration may reflect original organic pigments, staining, or mineral replacement.

Field identification & locations

Identify it by the bilateral shell form, repeated radial ribs, growth lines, and—if visible—the hinge and muscle-scar anatomy; common sources include marine sedimentary deposits and beaches. Avoid acid tests, which dissolve calcite.