Sweet Husband found this tiny egg in our chicken nesting box the other night. Much as I want another banty soon, all our current girls are full-sized so it was a mystery.
Of course, the internet provided a quick answer. From Granny Miller:
Tiny or miniature size eggs in standard size hens are the natural result when a small bit of reproductive tissue or other small foreign mass enters the hen’s oviduct and triggers the regular formation of an egg. Inside the hen’s body the bit of tissue is treated exactly like a normal yolk and is swathed and enveloped in albumen, membranes and a shell and is eventually passed from the hen’s body. When it is laid it looks just like a regular chicken egg except that it is very little and teeny.
But you wanna hear the really weird part? Apparently, these eggs (also called "cock eggs" or "witch eggs") used to be a sign that your chickens were in league with the devil. In 1474, a chicken was even burnt at the stake--with the "solemnity" and witnesses that would have been required for a human witch--for laying such an egg.
While I have, at times, believed my hens to be possessed, I think a burning at the stake probably goes too far. The egg is in my refrigerator, and we're sticking to calling it by its pretty Victorian name--a fairy egg.