Could be a malformed egg. If it all passes then there may be no further problems, but I would keep an eye on her. If not all egg passes it could end up causing infection. I would still do a soak/bath and clean her up and check her over. If you can remove it, what ever it is, and get a good look at it, that would help. Despite the grossness. You can wear gloves. If it's still not all the way out you can sometimes assist by gently pulling with constant pressure and it might help her pass it. Don't pull real hard, you don't want to hurt her or cause her to prolapse. The warm bath will also help her relax. If you can ID what it is, just droppings built up, or something else, that would be helpful.