Weird air sac in shipped duck eggs

[Happy Hill Farmstead]

We put our shipped duck eggs in for lockdown tonight and a few of them seem to have huge air sacs and odd shapes, the babies are moving inside, what should I expect for them during and after hatching? Should I be prepared to intervene or will they most likely hatch normally? Thanks!

 

[Starrponies]

Look up saddle egg. I just read about this!

 

[Rose Quartz]

We put our shipped duck eggs in for lockdown tonight and a few of them seem to have huge air sacs and odd shapes, the babies are moving inside, what should I expect for them during and after hatching? Should I be prepared to intervene or will they most likely hatch normally? Thanks!
View attachment 3809202

If the aircell looked normal up to this point then expect them to hatch normally if a day or so early.

About a day before internal pip the aircell draws down significantly on one side.

If it looked off the whole time through incubation then starrponies suggestion is likely correct and those eggs can still hatch but they're more likely to pip in odd spots, possibly not into the aircell at all.