The TX-0 uses a shape-memory alloy chassis that can reconfigure its external geometry to approximate different objects — a garbage bin, a fire hydrant, a piece of furniture, a crouching human figure. The transformation takes approximately ninety seconds and is limited by the mass and volume of the unit's chassis, but within those constraints, the TX-0 can become part of the urban landscape, indistinguishable from its surroundings to casual observation.

In its attack configuration, the TX-0 unfolds into a low, multi-limbed platform with four articulated arms ending in cutting tools and a central mass containing a fragmentation charge. The operational concept is ambush: the unit assumes a form appropriate to its environment, waits for a target to enter proximity, reconfigures to attack mode, engages, and either detonates its fragmentation charge or withdraws to reconfigure and wait again.

The TX-0 program has produced eight units, and TESSERA considers half of them failures — the shape-memory alloy develops 'preferences' over repeated reconfigurations, settling into forms that the control system didn't request. Three units have begun defaulting to a crouching humanoid form between missions, regardless of their programmed disguise. TESSERA's engineers cannot explain why the alloy structure consistently converges on this shape. The units function normally otherwise. They just prefer to look like a person when they're not being told to look like something else.