I gave my hens lots of joghurt with crushed shells after this, as well as some apple cider vinegar in their water. Haven't had one since, thank goodness :).
The ball was soft. We cut it open, and there was yolk! So, it looks like it may be a deformed egg. The skin is soft and "membraney".
We are watching her to see if she lays another, or a regular egg.
One of my hens, I think it was my oldest (3 years old) laid this ball, it looks like it is filled with blood.
I checked all their vents for blood, and they are all acting very normal, so I cannot tell who laid this today.
Any ideas what it is?