Embryo in nesting box

[GlicksChicks]

It is very unlikely that an egg was incubating inside of her. I have had hens move eggs from one nesting box to another or from outside of the box into the box again. It could be possible that there was an egg layed somewhere where you couldn't see it and then a hen rolled it back in.

The liquids on the inside of a hen would not allow for an egg to start incubating. The bloom would still be wet and there would be no oxygen to an egg for it to make it that far.

 

[MiraBella Ranch]

Here's my idea...for your mystery embryo egg. I agree this chicken journey is an adventure! Same with the ranch in general! starting our fourth year on the ranch. I have encountered mystery eggs on the property. The first time, we were doing bull dozer work creating a horse arena and moving literally tons and tons of dirt that was hauled in. At the end of the day, I walked the area and found a chicken egg - unharmed nestled in the dirt! My young chickens weren't even laying yet! Neighbors (if they have coops) are several acres away.

So that happened again last year...I found an intact egg on my land...but I know the eggs my girls lay and this was not from my coop.

The next mystery was one day, I entered the coop, changed the plastic sheets under the roosts and spot cleaned the shavings on the floor. I saw the girls still in the nesting boxes and decided to do some other chores before coming back to collect the eggs. When I came back an hour or so later, I collected the eggs and almost stepped on one! There was a blue egg - (one of my girls') intact laying in the shavings right in front of the chicken's door. My girls would never have layed it there!

In addition, I have found a few broken egg shells around my property that are curiously "opened" and not broken in half.

So I would like to suggest that maybe that egg was from another neighborhood coop and someone furry is moving eggs between coops. It's a theory...as you seem to have no other?