The UT-1 is a 6-meter-long segmented tunnel-boring automaton originally designed for utility corridor expansion. Its front section houses a diamond-carbide rotating cutting head that can chew through concrete, rock, and structural steel. Behind the cutting head, a series of articulated body segments carry debris removal systems, structural reinforcement dispensers, and — in the combat variant — a passenger compartment for eight fully equipped operators who ride inside the machine as it cuts its way into a target building from below.

The UT-1 moves at approximately 2 meters per minute through solid concrete, meaning it can breach a building foundation in under ten minutes from an adjacent tunnel. The cutting head produces a distinctive low-frequency vibration that can be felt through floors and walls — experienced residents of the Shelf and Underworld can identify a Worm approach by the tremor in their bones. By the time the vibration is felt, the machine is already close.

The combat application turns the UT-1 into a breaching weapon. The machine cuts into a basement or foundation, the front section opens, and operators pour out of the machine's body directly into the target structure. The entry point is unexpected, the noise of the cutting head masks approach sounds until the final seconds, and the structural damage to the foundation creates additional hazards for building occupants. Ouroboros sells the combat variant under the designation 'Subsurface Access Platform' with documentation that never uses the word 'weapon.'