Rock Identifier
Trilobite Fossil (Phylum Arthropoda, Subphylum Trilobita) — fossil
fossil

Trilobite Fossil

Phylum Arthropoda, Subphylum Trilobita

AI-generated identification · may be incorrect

Composed of calcified chitin exoskeleton, segmented body divided into three lobes, hardness ranges from 3 to 5 on the Mohs scale, earthy luster, colors vary in shades of grey, brown, and tan.

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Physical properties

Composed of calcified chitin exoskeleton, segmented body divided into three lobes, hardness ranges from 3 to 5 on the Mohs scale, earthy luster, colors vary in shades of grey, brown, and tan.

Formation & geological history

Formed during the Paleozoic Era, spanning from the Early Cambrian to the Late Permian period, through the rapid burial of marine arthropods in fine-grained sediment which replaced organic matter with minerals.

Uses & applications

Valuable index fossils for dating geological strata and widely sought after by fossil collectors and educational institutions.

Geological facts

Trilobites are one of the earliest well-known groups of arthropods, surviving for over 270 million years before going extinct during the Permian-Triassic extinction event.

Field identification & locations

Found worldwide in ancient marine sedimentary rocks, particularly shales and limestones. Collectors often split shale layers carefully to reveal preserved exoskeletons.

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

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