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

Trilobite Fossil

Phylum Arthropoda, Subphylum Trilobita

AI-generated identification · may be incorrect

Hardness varies depending on mineral replacement, typically calcite (Mohs 3); colors range from gray to brown; vitreous or dull luster; segmented exoskeleton with distinct cephalon, thorax, and pygidium.

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Physical properties

Hardness varies depending on mineral replacement, typically calcite (Mohs 3); colors range from gray to brown; vitreous or dull luster; segmented exoskeleton with distinct cephalon, thorax, and pygidium.

Formation & geological history

Formed through permineralization or carbonization in ancient Paleozoic marine environments, dating from 521 to 252 million years ago.

Uses & applications

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

Geological facts

Trilobites are one of the earliest well-known groups of arthropods, surviving for nearly 300 million years before going extinct in the Permian-Triassic extinction event.

Field identification & locations

Found worldwide in sedimentary marine shales and limestones; easily identified by their distinct three-lobed, segmented body structure.

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Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone) (Bioclastic limestone, composed chiefly of calcite (CaCO₃)) — sedimentary

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

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
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Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

sedimentary
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Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil