The UT-5 is a 3-meter serpentine automaton designed to pursue targets through tunnel systems, pipe networks, and confined spaces where humanoid or multi-legged platforms cannot operate. Its body is segmented into twelve articulated sections, each with independent locomotion — allowing the Lamprey to navigate right-angle bends, vertical shafts, and pipe junctions without slowing. The front section contains a high-definition camera, thermal sensor, and a single-use taser discharge system designed to incapacitate targets at contact range.

The Lamprey was designed for Underworld pursuit operations — chasing targets through the maze of tunnels beneath GLMZ where human pursuers lose their way and larger drones can't fit. The unit's navigation system builds a real-time map of the tunnel network as it moves, meaning every Lamprey deployment expands Arcturus's understanding of the Underworld's layout. This mapping capability may be the unit's actual primary purpose, with the pursuit function serving as justification for sending mapping equipment into territories that would otherwise be inaccessible.

The psychological impact of the Lamprey is significant. In the enclosed spaces of the Underworld, the sound of something sliding through pipes behind you, getting closer, is described by survivors as worse than being shot at. The unit's articulated movement produces a rhythmic scraping sound that echoes through tunnel systems and makes directional identification difficult.