We know it can exist as a solid, liquid and gas, but put it under extreme pressure and it converts into a freaky fourth state called tunneling, and it may even freeze at temperatures it would normally boil. But now, researchers have found that water actually has two different liquid forms, and its weirdness may come from the relationship between those forms.

The finding started with the understanding that ice exists in different forms. When we freeze water at home, its molecules line up in a crystalline structure that's fairly ordered and symmetrical. But out in space, ice tends to take on a less structured, amorphous form, and even then, there are two different types with low and high densities. It's long been thought that this could apply to its liquid form, but it's never been directly observed – until now.