sedimentary
Brachiopod Fossil
Phylum Brachiopoda (replaced by Calcite or Silica)
Hardness: 3-4 (if calcite) or 7 (if silica); Color: Gray, tan, or brown; Luster: Dull to earthy; Structure: Bilateral symmetry with fan-shaped ribbing; Cleavage: None (fossilized shell)
- Hardness
- 3-4 (if calcite) or 7 (if silica)
- Color
- Gray, tan, or brown
- Luster
- Dull to earthy
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Physical properties
Hardness: 3-4 (if calcite) or 7 (if silica); Color: Gray, tan, or brown; Luster: Dull to earthy; Structure: Bilateral symmetry with fan-shaped ribbing; Cleavage: None (fossilized shell)
Formation & geological history
Formed through the process of permineralization or replacement in marine sedimentary environments. These organisms flourished during the Paleozoic era (541 to 252 million years ago).
Uses & applications
Primarily used for geological dating (index fossils), scientific research, educational purposes, and as collector specimens.
Geological facts
Brachiopods are often called 'lamp shells' because their shape resembles ancient oil lamps. Although they look like clams, they are biologically distinct and have symmetry across the valves rather than between them.
Field identification & locations
Identify by looking for a 'hinge line' where two shells meet and distinct radial ribbing. Commonly found in limestone outcrops, road cuts through sedimentary rock, and dry creek beds.
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