fossil

Fossil brachiopod shell

Likely a spiriferid brachiopod; fossilized calcium-carbonate shell (mostly calcite)

AI-generated identification · may be incorrect

Ribbed, bilaterally symmetrical shell with radiating costae and a pronounced fold-and-sulcus pattern; Mohs hardness about 3, vitreous to pearly luster, and commonly gray, cream, or brown. Brachiopods are not rocks in the strict classification, but are geological fossils.

Identified August 16, 2026More fossil →

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Physical properties

Formation & geological history

Marine brachiopod originally secreted a calcite shell; burial and mineral preservation occurred in Paleozoic seafloor sediments, commonly Devonian–Permian (about 419–252 million years ago).

Uses & applications

Primarily a collector and educational specimen; polished examples may be used decoratively, but it has negligible industrial or jewelry use.

Geological facts

The shell’s symmetry is the strongest clue: brachiopods are symmetric across each valve, unlike most bivalve mollusks, whose symmetry is between valves.

Field identification & locations

Look for strong radial ribs, a central fold/groove, and two unequal valves; common fossil-bearing limestones and shales worldwide, especially North America, Europe, and China. Exact genus requires the hinge and both valves.