Poultry Talk Ontario (pto.ca)

So I know that shipped eggs can have detached or saddle air sac but have you ever seen this in your own backyard eggs? My one barred rock lays these on a regular basis. The air sac is often on the side of the egg. I also had a few that looked normal until the air sac started increasing during incubation and then appeared saddled at about 10-12 days of incubation. Those embryos didn't make it. The eggs I've seen this way are from 5 year old hens but not all from the same girl.