Pictured above is a photo of some houses in Bermuda (via here), an idyllic island nation in the North Atlantic Ocean. The pastel-colored walls are what probably catch your eye -- beautiful, right? -- but let’s today focus on the roofs. They’re all basically the same, and that’s not an accident. It’s a survival trait.

Bermuda, being an island, is surrounded by water. But the water, as anyone who watched a young Ben Ben Affleck in Voyage of the Mimi in eighth-grade science can tell you, isn’t good for us humans to drink. For those who didn't, though, the American Museum of Natural History can explain it: "If you drank seawater, the salt would get absorbed into your blood along with the water. That would make your blood too salty. So, your kidneys would have to remove the salt. But to do that they would need to use even more water! That's why drinking seawater would just make you thirstier. It can even make you sick if you drink it too often." Bermudans, therefore, need to find another source for their drinking water.

And unfortunately, there isn't one to be found -- at least not permanently. There are no freshwater rivers, lakes, or streams across the entire island. The only source of drinkable water comes from the sky.

Which is why the roofs are the way they are. Bermuda has huge amounts of limestone deposits, and therefore, limestone is a relatively inexpensive option if you're looking to build a house. It's a resilient building material that holds up well in hurricanes, which is important when you're out there in the middle of the Atlantic Ocean. Most if not all of the homes seen above are made from limestone -- including the roofs. But the roofs do more than just resist storms. They also turn that weather into drinking water. As seen below, via the BBC, the roofs are built with a step-like pattern which, as the BBC explains "are designed this way to harvest rain. The steps slow down heavy rainfall helping the gutters to collect the water and store it in a tank under the house."