sedimentary

Brachiopod Fossil in Limestone

Phylum Brachiopoda, Class Rhynchonellata

AI-generated identification · may be incorrect

Hardness: 3 (limestone matrix); Color: Tan/Grey; Luster: Dull/Earthy; Structure: Symmetrical bivalved shell with ribbing; Cleavage: None; Specific Gravity: Approx 2.7

Hardness: 3 (limestone matrix)
Color: Tan/Grey
Luster: Dull/Earthy

Identified May 2, 2026More sedimentary →

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Physical properties

Hardness: 3 (limestone matrix); Color: Tan/Grey; Luster: Dull/Earthy; Structure: Symmetrical bivalved shell with ribbing; Cleavage: None; Specific Gravity: Approx 2.7

Formation & geological history

Formed in shallow marine environments during the Paleozoic or Mesozoic eras (approx. 50-500 million years ago) through the mineralization of marine shells within lime mud.

Uses & applications

Scientific study, educational tools, fossil collecting, and occasionally used in limestone production for construction.

Geological facts

Brachiopods are not clams; while they look like bivalve mollusks, they are their own distinct phylum. They survived the 'Great Dying' mass extinction, though their diversity was drastically reduced.

Field identification & locations

Identify by radial ribbing and bilateral symmetry across the surface of the shell valve. Commonly found in limestone road cuts, creek beds, and quarries globally.