it's 7 days old and I candled when I got them and the yolk looked a little bigger than the others but i didn't think much of it. and no it doesn't smell.Does it smell?
Edit: did you candle the eggs before you put them in? I like to candle on day 1 mostly to look for cracks or anything that might tell me the egg is a waste of time to incubate but it would also catch a bad eggs as well.? Also do you know where the egg came from and how old it is?
they're ameraucana eggs so they're blueish green and some are more whiteIf it were me (and you can take this with a grain of salt) I would remove the egg. In my eyes better safe than sorry. A bad eggs can ruin the whole batch and cause problems with your next hatch if it introduces bacteria in your incubator that you don't get out before your next batch. I don't know but I would bet the egg is bad if all you're seeing is black on day 7. Just curious is this a dark egg like Maran or welsummer.