A new study has finally spelled out how some weird-looking land forms in Iceland came to be. Sadly, the local legend that they were tossed there by warring trolls turns out to be wrong—but the real reason is pretty interesting in its own right. They're lava pillars, formed when water and lava mix, according to University of Buffalo researchers. But what makes these pillars unique is that they're the first of their kind to be found anywhere on land, reports LiveScience. The pillars are hollow, scarred, rocky things up to 8 feet tall and 3 feet wide. "I was so excited," says co-author Tracy Gregg. "As soon as I saw these things I knew what they were."
That's because she had seen similar pillars on the ocean floor. They're able to form there, thanks to intense pressure, explains Science. But on land, it's near impossible because the meeting of lava and water typically results in an explosion of steam. So what happened? The study theorizes that the pillars in Skaelinger Valley were formed when a massive eruption in 1783 spilled lava for eight months. But the lava moved so slowly that when it finally made contact with water in the valley, it did so in a "kinder, gentler" manner that avoided an explosion. The find opens up the possibility of more lava pillars elsewhere on land, but Gregg will be looking beyond Earth. If the pillars can be found in high-resolution images of Mars, she says it would be a sign that the planet once had water. (Meanwhile, Jupiter might have diamond rain.)