Scientists are getting to the bottom of the mysterious skyscrapers of ice that shoot up from Pluto’s surface.

Data from NASA’s New Horizons spacecraft suggests that the features near its equator that look like “giant knife blades” formed when methane ice became eroded, “leaving dramatic crests and sharp divides,” the space agency explained Tuesday.

That ice accumulated in the first place when methane, a compound which is found in Pluto’s atmosphere, became frozen and built up on the ground in areas of high altitude in the same way that frost covers the surface of Earth.

But extreme changes in the climate — which a study in the journal Icarus referred to as “excursions in Pluto’s climate — that heated up the icy structures would have transformed the frozen methane directly from a solid into a gas, a process called sublimation that skips the liquid phase of matter.

“When we realized that bladed terrain consists of tall deposits of methane ice, we asked ourselves why it forms all of these ridges, as opposed to just being big blobs of ice on the ground,” New Horizons team member and Ames Research Center scientist Jeffrey Moore said in the statement. “It turns out that Pluto undergoes climate variation and sometimes, when Pluto is a little warmer, the methane ice begins to basically ‘evaporate’ away.”

According to NASA, the finding tells scientists that Pluto, even though it has been demoted from a full-fledged planet into a dwarf planet, has a climate that changes over millions of years.

The ice blades on Pluto are similar to some you could find in areas of high altitude near Earth’s own equator. NASA said they are called penitentes, and they form when ice transforms directly into gas through sublimation and leaves behind the spiky shapes. But on Earth, these ice structures only grow some feet tall, while Pluto’s are hundreds of feet high.

“As a result of this discovery, we now know that the surface and air of Pluto are apparently far more dynamic than previously thought,” the space agency said.

The study also notes that the blades represent areas of high elevation that were previously unrecognized.

And knowing that the bladed terrain marks a high altitude area will help scientists better understand the topography of the rest of Pluto.

“This provides an opportunity to map out altitudes of some parts of Pluto’s surface not captured in high resolution, where bladed terrains also appear to exist,” NASA said. “Though the detailed coverage of Pluto’s bladed terrain covers only a small area, NASA researchers and their collaborators have been able to conclude from several types of data that these sharp ridges may be a widespread feature on Pluto’s so-called ‘far side,’ helping to develop a working understanding of Pluto’s global geography, its present and its past.”