Robots that 'bleed' like Arnold Schwarzenegger's Terminator have come one step closer to reality.
Scientists have created a plastic 'skin' that oozes red blood when cut.
It can also 'heal' itself, building tiny molecular bridges inside in response to damage.
The red 'blood' might sound like a pointless Halloween novelty – but the idea is that the 'skin' can warn engineers that a structure such as an aicraft wing has been damaged.