fossil

Fossil brachiopod shell

Likely a ribbed orthid or productid brachiopod; exact genus cannot be determined from this image

AI-generated identification · may be incorrect

A small, oval, strongly ribbed shell with bilateral symmetry and brown-gray mineralized surface; original shell is calcium carbonate, commonly replaced or infilled by silica or calcite. Hardness is typically about 3 for calcitic material, with dull to slightly pearly luster and prominent radial costae.

Identified August 29, 2026More fossil →

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Physical properties

Formation & geological history

Brachiopods were marine filter-feeders, especially abundant in Paleozoic seas; comparable specimens are commonly Ordovician–Permian, roughly 485–252 million years old. The shell was buried in marine sediment and preserved through mineralization.

Uses & applications

Primarily a teaching, collecting, and display specimen; it has little industrial or jewelry value.

Geological facts

Brachiopods resemble clams but have different shell symmetry: each valve is bilaterally symmetrical, unlike the two unequal valves of most bivalves.

Field identification & locations

Look for a single shell with ribs radiating from a beak or hinge and symmetry down the midline; identification is strongest if the opposite valve, hinge, or rock matrix is present. Common in Paleozoic marine limestones worldwide, including North America, Europe, and Australia.