This Desert Was Once an Ocean — And the Proof Is Hiding in Plain Sight

Seashells in the Sahara? The story behind them will rearrange your sense of time.

Scattered across parts of the Sahara, travelers keep finding something that shouldn't be there: fossilized seashells and the bones of ancient whales.

Millions of years ago, a warm shallow sea covered swaths of what is now North Africa, teeming with marine life whose remains are now baking under desert sun.

Even more recently — just a few thousand years ago — much of the Sahara was green savanna, dotted with lakes, hippos, and human settlements. Ancient rock art still shows people swimming.

The takeaway is dizzying: the driest place you can imagine is just one chapter in a landscape that keeps flipping between ocean, grassland, and sand.