Look what was found in the coop. I have a few different pullets starting to lay in this coop. I am guessing this is from a young EE who has been laying a lot of double yolkers.
I have had some like that in the past. its a shell less egg.
If it only happens occasionally its nothing to worry about.
It is probably caused but the chickens being stressed by something, (scared by others or dogs etc) being interrupted when laying etc.
If its happening more and more often then it can be a sign of something else.
Make sure the chickens have access to some form of grit as this will help when making the shell and also make sure their diet is well balanced.
Hopefully that helps. Also double yolkers are often just when the hormones are messed up a little in their cycle. that should sort itself out on its own. Sometimes i have had double yolkers when they first start laying.