In a dish of water in Cambridge, Massachusetts, a new kind of robot stirs, its tentacles twitching. Squashy and soft, this robot is different from its technological ancestors – Octobot runs without a power cable or rigid electronics, moving autonomously – if still clumsily – through the world. Soft robots have long been heralded as a new class of machine. But their tethers, and the electronics needed to control their movements, have held them back. Developed by Michael Wehner and colleagues at the Wyss Institute for Bioinspired Engineering, Harvard University, it's a big step towards fulfilling the potential of soft robots.