The idea of a "tentacle manipulator" developed by the U.S. Army is already scary enough by name alone. Toss it that this thing can open doors, then it gets even scarier. The manipulator comes in peace, though, and it could even save lives.
With a tentacle manipulator like the one you see above, the robots already deployed by the U.S. Army that help diffuse bombs or scout buildings would have greater dexterity. They'd now be able to grasp and rotate or pinch and lift — just like if they had a hand. That'd allow them to do everything from turn the knob on a door to lift an object covering an explosive.
What's more, each tendril of the tentacle manipulator is equipped with light detection and ranging gear (or LIDAR) and a 3D imager. This is pretty key, as it allows for an operator to accurately work with the manipulator, rather than trying to move it from an external view.
Right now, the snake-like attachment is being developed in collaboration with Carnegie Mellon University, and the future could see a tentacle manipulator that could propel itself through the water, or one that is developed on a much larger scale.