This multigait soft robot is composed of elastomeric polymers; the soft robot is pneumatically activated, undulating as it walks.
(Multigait soft robot video)
This particular robot (which comes from George M. Whitesides' lab at Harvard) distinguishes itself by being capable of several unique gait styles including walking, crawling, and slithering. Each of these gaits is controlled by pumping air at up to 10 psi into a succession of limbs, inflating and deflating elastomer compartments to provide temporary structure and rigidity. In addition to slipping through gaps, the robot can make it across things like felt cloth, gravel, mud, and Jell-O (don't ask).
SF readers may be thinking of the "moldies" from Rudy Rucker's 1997 novel Freeware:
Monique's tissues had at least three other basic attractor modes as well: the spread-out "puddle" shape she used for soaking up sun, the seagoing "shark" shape, and the rarely used "rocket" shape...
(Read more about Rucker's moldies)
I enjoy soft robots; read more about the different kinds: