This was in the news--> A person named Cookie Smith got an egg inside of another egg--- this news article gives some explanations...it would be nice for some statistics. e.g. weight, type of hen...etc. "Oh my word," Smith remarked to the Abilene Reporter News journalist as a complete egg slid out of the cracked shell, along with a bright yellow yolk and slippery white. "Would you look at that?" Researchers say this kind of "double egg" is relatively rare and forms when "unusual contractions" force a developing egg traveling down an oviduct to move back into the ovary, where it is surrounded by another egg. Then, the concentric eggs are delivered as one, the Austin Statesman reported. Experts said the eggs were probably safe to eat, but Smith and her husband, Leonard, declined. "No way. It may be fine, but it's a mutant egg," she told the Abilene Reporter News. "Its DNA may be messed up or something." http://www.huffingtonpost.com/2012/...-egg-inside-super-mutant-texas_n_1562733.html
Had one of those from one hen. Had another hen die because her huge egg within an egg dropped into the abdomen and there was no way to save her. It happens on occasion.
Hi Speckled Hen, I've never had one, and from what you say---I hope I never will--- From time-to-time, I see posters in BYC showing them, but I never heard that explanation so clearly before this news article.