fossil

Brachiopod Fossil

Phylum Brachiopoda (poss. Order Spiriferida or Rhynchonellida)

Hardness: 3-4 (calcite) or 7 (if silicified); Color: Grayish-tan to translucent; Luster: Dull to waxy; Features: Symmetrical bilateral valves with prominent growth lines or ribbing.

Hardness: 3-4 (calcite) or 7 (if silicified)
Color: Grayish-tan to translucent
Luster: Dull to waxy

Identified July 11, 2026More fossil →

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Physical properties

Hardness: 3-4 (calcite) or 7 (if silicified); Color: Grayish-tan to translucent; Luster: Dull to waxy; Features: Symmetrical bilateral valves with prominent growth lines or ribbing.

Formation & geological history

Formed through the permineralization or recrystallization of marine invertebrates that lived on the ocean floor. The specimen is likely from the Paleozoic or Mesozoic era (between 66 and 500 million years old).

Uses & applications

Primarily used for educational purposes, scientific study (stratigraphy), and amateur fossil collecting. Small specimens are sometimes used in wire-wrapped jewelry.

Geological facts

Brachiopods are often called 'lamp shells' because they resemble ancient oil lamps. While they look like clams (bivalves), they are biologically distinct, with shells that are symmetrical across the valve rather than between valves.

Field identification & locations

Identified by the distinct nested ribbing pattern and overall 'D' or shell shape. The location (North Dakota region) is consistent with marine deposits from the Williston Basin, where such fossils are common in glacial drift or local bedrock.

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