Leathery egg with tube attached to another broken leathery egg?

[anemone12]

I have a flock of 10 chickens total, they have been laying since February. I found a leathery egg on the poop board today, and wouldn't usually think twice about it since this is only the second time I have found one, however, it had a tube attached to it that was the same material as the egg, and on the other end was a broken piece of membrane with yolk and white matter, like a second egg that broke upon hitting the board. The odd egg was quite large in size but only contained one yolk. I have not been able to find any information on this occurrence and was hoping someone else may have experienced the same or has some information on why this happens and if there is something wrong?

 

[distincthead]

I've seen one of those before, and the chicken that it came from layed perfectly fine eggs after that weird one, but I'm sorry to say I don't know what on earth causes it. I hope someone with more knowledge can figure it out for you. I guess it can happen with new layers and from what I've read, not cause for alarm.