I have 41 eggs in the incubator. Since they are all blue, green or dark brown it is very difficult to see inside. They all look like the spaces are being filled and growing inside the shell but one egg seems to have a slight sulpher (sp?) odor. I have been trying to find a blood ring and did see a thicker dark line just under the yolk area, So at 7 days with the egg pointing down I can see the airspace, about 1 1/2 inches of darkness, then a thick horizontal line and then clear. What do you think?