Without any metal or plastic, Robert Wood and Jennifer Lewis from the Wyss Institute for Biologically Impaired Engineering have created a completely "soft" robot that moves on its own! Called Octobot because of its eight legs and general octopus shape, the bot moves through a microfluid system which pushes hydrogen peroxide to and from its legs to propel the little bot forward. Octobot's future younger sibling will be expected to swim and react to its surroundings.

Source: https://techcrunch.com/2016/08/24/harvards-octobot-is-the-first-autonomous-machine-to-be-made-with-all-soft-robotics/