When you think about life beyond Earth, you likely think of it occurring on a somewhat Earth-like planet. A rocky world, with either a past or present liquid ocean atop the surface, seems ideal. But that might not even be where life on Earth originated! Deep beneath the Earth’s surface, geologically active hydrothermal vents currently support diverse colonies of life without any energy from the Sun. Saturn’s icy moon, Enceladus, has a subsurface ocean unlike any other world we’ve yet discovered.