As seen on 4-H EGG Cam at lancaster.unl.e.... Candling is basically shining a bright light at an egg in a dark room to see how the embryos are growing. This candling video shows three kinds of eggs: "winners" (embryos are developing), "quitters" (embryos have quit growing) and "yolkers" (eggs were never fertilized). In many of the winners, you can see the embryo moving. At day 7, chicken embryos are about the size of a dime. If you leave yolkers or quitters in your incubator, they will rot and get very smelly, so we remove them from the incubator.