The Eatr, Energetically Autonomous Tactical Robot, is a steam-powered machine that eats twigs, leaves and plants for fuel. It’s only in testing stages now, but advanced models could power themselves for months, and work as roving turrets or front-line ambulances. The military use of autonomous, organic material-devouring robots has led to rumours that Eatrs might approach battlefield-strewn corpses. But its developers have put that idea to rest. They say the Eatr has special sensors which only allow it to eat certain types of material.