Glaciers once inched toward the sea, gouging rocks. When the ice masses melted, they infused oceans with nutrients that may have shaped how life evolved, a study found.

Earth was a very different place during its Cryogenian period, around 700 million years ago. It was covered head-to-toe in kilometers-deep dice as huge frozen rivers churned across the planet’s rocky surface.

Imagine floating in space, gazing on a frozen white orb. The ball hangs in the void, lonely and gleaming in the light from its star. From pole to equator, the sphere is covered in a thick crust of ice.

Glaciers once inched toward the sea, gouging rocks. When the ice masses melted, they infused oceans with nutrients that may have shaped how life evolved, a study found.