We're seven chicks in to our first incubator hatch - we've had multiple hatches before but always with a broody, so no fuss on our end. I've still got nine eggs in there, five are pipped and four don't appear to be through the window - although one chick exploded out of an egg that I didn't think was pipped (that I could see) so who knows. Anyway, it appears as though several - two that I've seen so far, possibly a third - have issues with the naval opening. Specifically, there's a protruding bump, and it hasn't closed. The first three to hatch were up and moving around quickly, then #4 popped out but just sort of layed there....when it started moving it flipped and I could see the bump. It was pretty large, and I was pretty certain that the chick would die, but I left it and now it's moving around well, dry, and the bump seems smaller. Chick number six just had the same thing happen about 15 minutes ago - finally got out (s/he was stuck for almost 5 hours with no progress and was starting to look like s/he was going to give up when s/he got out) but is laying there very quietly on it's belly, and I can see the bump from it's backside. This one seems worse off than the other, and I'm pretty sure it's going to die....I'll give it a chance though, and let nature decide what will happen. So....what went wrong? Is this maybe a normal thing to see with hatches, but since mama chicken has done it all and I don't even get a hand on the babies till they're several days old I don't see it? Something wrong with our temp or humidity? Our temp was consistently 99.5-100.5, and I kept the humidity around 40%. Lockdown at day 18, temp steady and raised the humidity to 55-60%. They're hatching today on day 20. We put in eggs a variety of age - the oldest were 10 days (we wanted to see what they'd do) and some were 24 hours old. Our hens and rooster are all healthy. The chicks with the issues - one was a 10 day old egg, one was a 24 hour old egg. Any thoughts?