Researchers from Carnegie Mellon University Robotics Institute have developed a burrowing robot.

"One use case is for this robot to drive or be air-dropped to a location close to a target, bury itself to be hidden, perform video surveillance, and send that video back to an operator."

Just look at it burrow into sand... and then resurface. It also has the capability for surface locomotion.

Hmmm... haven't we read of this variety of robot before? Maybe we've seen it on dvd? ;)

via spectrum.ieee.org