I'm new to incubating. I have a small sized incubator, currently with only 7 eggs. I know 4 of them are for sure developing as I can clearly see the eye/blood veins. The other 3 eggs, I'm not so sure they are on track. I can't really tell because they are opaque. Should I keep them or throw them away? I would have to throw out a developing egg, but if I keep one, I heard they can explode. Also, are there any given sogns to tell if an egg isn't developing? Thanks!!!