system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why do bags of dry beans have rocks in them?

Just ordinary bags of dry beans you get at a supermarket. They have rocks mixed in with the beans. Cheaper brands have more rocks, but I think all brands get a rock now and then.

Why do bags of beans have rocks?

More importantly, how do I separate the rocks other than pouring the beans out and physically picking the rocks out as I find them?
gpt
The rocks are left over from the soil where the beans grew. Some get picked up in the harvesting process, and those with size and density similar to a bean are difficult to sort out automatically so some are accidentally left in.