Serious Eats
An Egg Within an Egg
If you cook with bell peppers, you've probably cut one open at some time and have seen the phenomenon of the pepper within a pepper. But an egg within an egg is a little more freaky and rare.
It was the first Sydney University poultry science professor Tom Scott had seen in his 30-year career. He says a normal egg disturbed in the shell gland could move back up into the oviduct and start production all over again, resulting in an egg inside an egg.
Sorta puts a new spin on the "which came first" debate.