fossil

Enrolled Trilobite Fossil

Phylum Arthropoda, Class Trilobita (likely Calymene or Flexicalymene)

Hardness: 3-4 (calcite Replacement); Color: Brown, tan, or grey; Luster: Dull to earthy; Structure: Segmented exoskeleton with cephalon, thorax, and pygidium visible; Form: Enrolled (spherical) defensive posture.

Hardness: 3-4 (calcite Replacement)
Color: Brown, tan, or grey
Luster: Dull to earthy

Identified July 18, 2026More fossil →

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Physical properties

Formation & geological history

Formed during the Paleozoic era (approx. 450 million years ago) in shallow marine environments. The organism was buried in sediment, and through permineralization, minerals replaced the organic structure.

Uses & applications

Scientific study of evolution, educational tools, and highly decorative collector's items.

Geological facts

Trilobites are one of the earliest known groups of arthropods. The 'enrolled' position is a defensive posture similar to a modern pill bug, used to protect their soft underside from predators.

Field identification & locations

Identified by the distinct repetitive ribbing (pleura) and the curved, head-to-tail enrollment. Commonly found in limestone and shale deposits in places like Ohio, Morocco, and Russia.

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