As if there weren't enough real jellyfish around to trigger our thalassophobia, researchers at Virginia Tech have created Cryo -- an eight-armed autonomous robot that mimics jelly movement with the help of a flexible silicone hat. The man-sized jellybot altogether dwarfs previous efforts, hence the upgrade from small tank to swimming pool for mock field tests. And unlike the passively propelled bots we've seen recently, Cryo runs on batteries, with the researchers hoping to better replicate the energy-efficient nature of jelly movement to eventually increase Cryo's charge cycle to months instead of hours. That's also the reason these robotic jellyfish are getting bigger -- because the larger they are, the further they can go. Potential uses include ocean monitoring and perhaps clearing oil spills, but the US Navy, which is funding the work, sees an opportunity to recruit jellies for underwater surveillance -- a job the researchers say is suited to their natural-looking disguise. But, before the tables are turned, you can spy on Cryo for yourself in the video below.