I'll link these so you can see that shells often are not perfect. There is nothing wrong with that egg as far as safe to eat. It's fine. It does not hurt the hen. The hen is fine.
We are so used to perfection from the commercial egg producers that many people don't realize the range of stuff Mother Nature throws at the hens. If a customer saw that they'd probably freak out where people used to collecting their own eggs instead of buying them soon realize all kinds of weird things can happen. Usually nothing is really wrong, it's just some variety in the natural world.