Rock Identifier
Spirifer Brachiopod Fossil (Phylum Brachiopoda, Order Spiriferida) — fossil
fossil

Spirifer Brachiopod Fossil

Phylum Brachiopoda, Order Spiriferida

AI-generated identification · may be incorrect

Mohs hardness 3-4, gray to brown color, dull to earthy luster, bilateral symmetry with prominent radial ribs and hinge line.

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Physical properties

Mohs hardness 3-4, gray to brown color, dull to earthy luster, bilateral symmetry with prominent radial ribs and hinge line.

Formation & geological history

Formed through permineralization of ancient marine invertebrate shells in shallow Paleozoic seas, approximately 300 to 500 million years ago.

Uses & applications

Valued by fossil collectors, educational displays, and used in biostratigraphy to date sedimentary rock layers.

Geological facts

Spirifers are among the most recognizable extinct marine fossils, characterized by their butterfly-shaped shells and spiral internal support structures.

Field identification & locations

Found worldwide in sedimentary limestone and shale formations. Identify by distinct radial ribbing and pointed hinge line.

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Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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Weathered fossil bone fragment (identification uncertain)

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