fossil

Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

AI-generated identification · may be incorrect

Hardness: 3-4 (Calcite matrix). Color: Rusty reddish-brown exterior (Iron oxides), tan to grey interior. Luster: Dull, earthy. Structure: Sedimentary nodule containing marine imprints.

Hardness: 3-4 (Calcite matrix)
Luster: Dull, earthy

Identified July 14, 2026More fossil →

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Physical properties

Hardness: 3-4 (Calcite matrix). Color: Rusty reddish-brown exterior (Iron oxides), tan to grey interior. Luster: Dull, earthy. Structure: Sedimentary nodule containing marine imprints.

Formation & geological history

Formed during the Paleozoic era by the accumulation of minerals around a biological nucleus in soft sediment, later hardening into a nodule. Often millions of years old.

Uses & applications

Educational specimens, fossil collecting, and decorative display.

Geological facts

Concretions are often mistaken for dinosaur eggs or meteorites due to their round, unusual shapes. This specimen specifically shows marine fauna preserved in a sedimentary matrix.

Field identification & locations

Identify by looking for distinct biological patterns (ribbed shells/columns) embedded in a different rock matrix. Commonly found in shale or limestone outcrops near ancient sea beds.