This nice man on YouTube came into possession of a rather large egg. He cracked it open, and to his surprise, there was a whole other egg inside of it. It is incredible:
There is a technical explanation for all this, the Associated Press reports:
According to a web video by the National History Museum in the United Kingdom, such a “double egg” is relatively rare. One forms when “unusual contractions” force a developing egg traveling down an oviduct back into the ovary. There, it is surrounded by another egg, with the concentric eggs being delivered as one.
It’s like the Russian nesting doll of eggs. We want one. (But, uh, maybe not to eat. Nobody seems to have been willing to sack up and eat one of these mutant eggs yet.)
The incredible, maybe edible double egg, Modern Farmer.