As they flew over the sweeping Siberian tundra, a Russian TV crew recently spotted an intriguing feature: a crater more than half a football field deep gouged from the frozen ground. Blocks of ice and dirt lay hundreds of feet away from the crater, flung from the deep scar on the surface.This is just the latest in a series of such curious craters discovered in the Siberian Arctic, after the first was identified in 2014. Scientists believe they form from blasts of methane and carbon dioxide gas trapped within mounds of dirt and ice—a phenomenon that may be increasingly common as the climate warms. But much remains uncertain.“We still don’t know what’s going on,” says Sue Natali, a permafrost expert at the Woodwell Climate Research Center in Falmouth, Massachusetts. “And is it going to happen somewhere else?”Recent studies of other craters point to one likely mechanism: cryovolcanism, in which eruptions take the form of frosty mud or slush rather than fiery molten rocks. Such phenomena are well known elsewhere in our solar system, such as on Saturn’s watery moon Enceladus. But cryovolcanism is thought to be uncommon on our planet. Studying these Siberian features could provide clues to what’s happening on those far-flung worlds.