They're like volcanoes on earth, but way cooler.
NASA has spotted possible ice volcanoes in the past, including on Saturn's moon, Titan, and on Pluto. Now, NASA has announced that even Ceres, the closest dwarf planet to the sun, has an ice volcano mystery going on!
These ice volcanoes are found on icy worlds. And rather than erupting with molten rock, they erupt volatiles like water, methane and ammonia.
Volatiles are chemicals that have very low melting points and for the most part remain as a solid inside icy planets and moons. For example, methane melts when heated to minus 182 degrees Celsius.
As Earth is a pretty warm place, methane is usually found as a gas here, but on super-cold worlds like Pluto, it's usually found as solid ice. However, if something heats the interiors of these worlds - like radioactive decay - methane and other volatiles will melt and erupt to the surface.