How many pairs of jeans have you owned in your life? Twenty? Fifty? But in all that denim-wearing time, we bet you’ve never thought about that tiny extra front pocket for more than a fleeting second, if that.

In fact, it’s probably been more of a nuance in your life, as you push past it to stow your keys in the bigger pocket before heading out the door.

But what is it for exactly?

It turns out that small pocket on the top right side your jeans was originally created, wait for it … a watch.

“It appears on the oldest pair of waist overalls — the original name for jeans — in the Levi Strauss & Co. archives that date back to 1879,” said Tracey Panek, a historian for Levi Strauss & Co.

Those original copper-riveted jeans had a tiny pocket to hold small pocket watches for working men, from carpenters and miners to railroad engineers. And the design stuck ever since!

Nowadays, we’ve upgraded to telling time with smart watches and phones, that teeny pocket is usually empty, but we love the idea of rethinking it for this generation’s trinkets.