sedimentary

Brachiopod Fossil in Shale

Phylum Brachiopoda (often species of Order Spiriferida or Rhynchonellida)

AI-generated identification · may be incorrect

Hardness: 3-4 (matrix), color: grey to dark carbonaceous grey, luster: dull/earthy, structure: bilateral symmetry across the valve (shell), often showing distinct ribbing or costae.

Identified March 12, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (matrix), color: grey to dark carbonaceous grey, luster: dull/earthy, structure: bilateral symmetry across the valve (shell), often showing distinct ribbing or costae.

Formation & geological history

Formed through the lithification of marine mud and silt containing the remains of marine invertebrates. Most common in Paleozoic strata (approx. 541 to 252 million years ago) in shallow sea environments.

Uses & applications

Primarily used for geological dating (index fossils), educational purposes, and private fossil collections. Shale is also a source for ceramic materials and oil/gas exploration.

Geological facts

Brachiopods are 'living fossils'; while they dominate the Paleozoic fossil record, a few species still exist today. Unlike clams, their shells are asymmetrical when viewed from the side but symmetrical across the face.

Field identification & locations

Identify in the field by looking for the fan-shaped 'pedicle' and 'brachial' valves in crumbly, layered sedimentary rock. Commonly found in road cuts and riverbeds in the Midwestern US and the UK.