The chickens surprised me today. Instead of the usual 4 or 5 eggs, they gave us 4½ eggs.
One was a tiny little thing, about the size of a yolk only.
The all-knowing Interwebs educated me:
“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.”
I haven't opened it, but I'm told to expect all egg white, and no yolk.