fossil

Fossil Brachiopod

Phylum Brachiopoda

Hardness varies by mineral replacement (often Mohs 3-7 if replaced by silica or calcite), grey-blue to brownish color, dull to vitreous luster, symmetrical shell structure with distinct valves, specific gravity around 2.6-2.7.

Identified July 29, 2026More fossil →

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Physical properties

Formation & geological history

Formed through the fossilization of marine invertebrate animals that lived in ancient shallow seas, typically dating from the Paleozoic era (over 250 to 500 million years ago) where organic shells were replaced by minerals during sediment burial.

Uses & applications

Used in paleontological research, educational displays, index fossils for dating geological strata, and popular among fossil collectors.

Geological facts

Brachiopods are one of the most common fossil types found globally, often mistaken for clams, though they belong to a completely different phylum with top and bottom symmetry rather than left and right.

Field identification & locations

Found worldwide in sedimentary rock formations, particularly limestone, shale, and siltstone deposited in ancient marine environments. Easily identified by their characteristic symmetrical two-valved shells and growth lines.