As astronomers examine the data the New Horizons probe has beamed back to Earth, the awesome deluge of Pluto factoids keeps coming: it’s got weird, wobbly moons, nitrogen ice glaciers, and, well, clouds. The latest bit of juicy Pluto gossip? The possibility of cryovolcanoes.

A large team of American astronomers and planetary scientists analyzed the peculiar mounds that thrust up from Pluto and Charon like astro-geological zits, in research published Friday in the journal Science. Of their geological examination, these lumps were the most mysterious:

More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago

Though they sound like Mortal Kombat Scorpion fatalities, cryovolcanoes are similar to lava volcano, but instead of trying to drown Pierce Brosnan in a flood of hot liquid rock, the spewing water is methane or ammonia. In our solar system, as far as we know, they tend to be a feature of moons; Voyager 2 spotted one of the first cryovolcanoes discovered on Neptune’s satellite Triton. Later images of Jupiter’s moon Titan indicate that cryovolcanism is a dominant feature of the moonscape, significantly altering the lunar topography.

The forces that cause a cryovolcano to erupt and an Earth volcano seem to be more or less analogous — a buildup of heat and pressure that forces liquidized materials to the surface. The big difference is what comes spurting out of the top — on Titan, for instance, astronomers hypothesize it’s “ammonia-water-methanol slurries” in lieu of molten rock. Luckily, ol’ Pierce and the rest of us Earthlings never have to worry about geological blasts of liquid ammonia, given that it boils at about minus 28 Fahrenheit.