Hello All, I am new to the duck egg thing so I have a question. Before I started to try to hatch the eggs, I had found two eggs in the yard. When I brought them in and cracked them open, there was a nickle sized, what looked to be mold spot on the egg yolk itself. I saw it in both eggs. I now have 4 eggs in the incubator and after candling them see the same sized dark spot where the air sack should be. I have looked an a million pictures of candled duck eggs online and have yet to see the same thing. Any insight would be great. I'm assuming this isn't normal but you know what happens when you assume. Please help. Thanks.