fossil

Fossilized Brachiopod

Brachiopoda (Phylum), likely Order Spiriferida or Rhynchonellida

Hardness: 3-4 (Calcite replacement); Color: Off-white, grey, or tan; Luster: Dull to earthy; Structure: Bilaterally symmetrical bivalve-like shell with radial ribbing (costae). Unlike modern clams, the valves are of different sizes but each valve is symmetrical.

Hardness: 3-4 (Calcite replacement)
Color: Off-white, grey, or tan
Luster: Dull to earthy

Identified July 2, 2026More fossil →

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Physical properties

Formation & geological history

Formed via permineralization or recrystallization of marine organisms in Paleozoic or Mesozoic shallow seas. These specimens are typically hundreds of millions of years old, often found embedded in limestone or shale.

Uses & applications

Primarily used for educational purposes, scientific study of paleoenvironments, and as affordable collector items. High-quality specimens are used in fossil jewelry.

Geological facts

Brachiopods are not mollusks, despite looking like clams; they belong to their own phylum. While they were incredibly dominant during the Paleozoic era, the Permian-Triassic extinction wiped out 95% of species.

Field identification & locations

Identify by looking for 'lamp shell' shapes with a distinct pedicle opening at the hinge. They are frequently found in road cuts, creek beds, and limestone quarries throughout the Midwest United States and the UK.

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