Paralejurus is a Devonian trilobite genus notable for its smooth, streamlined exoskeleton and reduced segmentation. Its fossils are common in marine deposits of North Africa and Europe, and indicate a benthic lifestyle.

Key features include a broad, vaulted central lobe, a large subtriangular tailshield, and subdued surface sculpture. The thorax often shows fused or reduced segments, and their holochroal eyes may be diminished in size.

These traits suggest adaptation to soft-bottom environments, likely involving burrowing or partial burial. Paralejurus reflects a shift toward simplification and substrate-oriented life within its lineage.