Thanks! It does seem to be a pattern, but since I have no idea which eggs come from whom, I don't know whether someone has just started to lay only these.
The skelter comes from here:
http://www.mannapro.com/products/poultry/the-egg-skelter/
Ezra
My four chickens are three years old - and someone has started laying miniature eggs with no yolks! See photos below. (Egg on the left is normal. Also how do you like my skelter?)
Have others experienced this? Is it just due to age?