I am incubating chicken eggs for the first time. I just candled all the eggs in my incubator for the first fertility check (4 days). All appear to be fertile, but one egg is solid all the way through. The candling guide just stated if an egg is clear all the way through, it's not fertile. I purchased the eggs in my incubator from a local farmer. Is it possible this one egg was sit on by the laying hen prior to purchasing and is close to hatching? Or is it just a bad egg and I need to pull it? I hate to pull it if it could hatch, but I also don't want to leave it in the incubator and risk it exploding, contaminating the incubator if it's bad. What should I do with it? There's no peeping coming from it or any cracks in the shell. Thanks in advance.