https://www.youtube.com/watch?v=PIpq6Hl6Jtc
When I was a kid I used to eat rocks. Debate goes around arguing that rocks are damaging to the esophagus and digestive track. I don't know if that's true or not, but I've never had a digestive issue at all.

People eat simple rocks every day. Salt is a rock, and people who take calcium pills or supplements are most likely digesting crushed up limestone.

Now, humans cannot digest rocks. Our saliva and stomach acids cannot break them down. You can eat them, but they'll simply pass through your system and come out the same way.