sedimentary

Brachiopod Fossil

Phylum Brachiopoda (Class Rhynchonellata)

AI-generated identification · may be incorrect

Hardness: 3 (if calcite replacement) to 7 (if silicified); Color: tan, grey, or brown; Luster: dull to earthy; Structure: bilateral symmetry across the valve; Cleavage: none; Specific Gravity: approx 2.7.

Hardness: 3 (if calcite replacement) to 7 (if silicified)
Color: tan, grey, or brown
Luster: dull to earthy

Identified June 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the fossilization of marine invertebrate shells in sedimentary environments, typically during the Paleozoic era (approx. 250-500 million years ago) via permineralization or recrystallization.

Uses & applications

Primarily used for scientific research, geological dating (index fossils), and as popular collector items for hobbyists.

Geological facts

Brachiopods look like clams but are unrelated; they have a pedicle (stalk) to anchor to the seafloor. They were once the most abundant shelled creatures on Earth before the Permian-Triassic extinction.

Field identification & locations

Identify by radial ridges (costae) and a hinge line. Commonly found in limestone or shale outcrops and riverbeds in the Midwestern United States and Europe.