fossil

Fossil brachiopod shell

Brachiopoda; likely a ribbed terebratulid or spiriferid brachiopod

AI-generated identification · may be incorrect

A ribbed, bilaterally symmetrical fossil shell with strong radial costae; originally calcite, typically Mohs 3–4, with dull to pearly luster and partially recrystallized texture. The visible convex valve and central fold/sulcus are characteristic of brachiopods, though the specimen is incomplete.

Identified September 17, 2026More fossil →

Explore Fossil brachiopod shell in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when a marine brachiopod shell was buried and mineralized in sediment, commonly limestone or shale. Exact age cannot be determined from the image; brachiopods range from Cambrian to Recent, with many similar fossils Paleozoic (541–252 million years ago).

Uses & applications

Primarily a collectible, educational, and decorative fossil; polished or mounted specimens may be sold as natural-history curiosities, not jewelry-grade material.

Geological facts

Brachiopods resemble clams but have bilateral symmetry through each shell valve rather than between the two valves. Their shells were commonly calcitic and may preserve fine growth ribs.

Field identification & locations

Identify by the strong radial ribs, unequal valves, and symmetry unlike a bivalve; acid testing is risky because calcite may fizz. Common in fossil-bearing marine limestones worldwide, especially Paleozoic strata.