 NASA's car-sized Mars Curiosity rover has been roaming the Red Planet since 2012, studying its climate and geology. Moving through a channel called Gadez Vala, scientists say was carved by water, Curiosity drove over a rock that split open, revealing yellow crystals. Analysis left the scientists astounded because they are pure elemental sulfur crystals, which up until now they thought needed specific Earth-like conditions to form. And there seems to be a whole field of them.