Ghost eggs. Boo!

I call them "ghost eggs."

A "ghost egg," or "wind egg," Is a sign that one of your chickens has just started to lay. (explained below by wikipedia) I have been able to recognize them now that I see them more frequently than before.  You can tell its a ghost egg by its little size nd round shape. With about twenty of our girls  laying regularly, the other twenty one are just starting to catch up.  We get these ghost eggs about two to three times a week.  They are pretty cool when you crack it open and see no yolk. 

The dogs like them very much too:)

Yolkless eggs

Eggs without yolk are called "dwarf" or "wind" eggs.^[8] Such an egg is most often a pullet's first effort, produced before her laying mechanism is fully ready. In a mature hen, a wind egg is unlikely, but can occur if a bit of reproductive tissue breaks away, stimulating the egg producing glands to treat it like a yolk and wrap it in albumen, membranes and a shell as it travels through the egg tube. This has occurred if, instead of a yolk, the egg contains a small particle of grayish tissue. An archaic term for a no yolk egg is a "cock" egg.^[9] Since they contained no yolk and therefore can't hatch, it was traditionally believed that these eggs were laid by roosters.^{[citation needed]} This type of egg occurs in many varieties of fowl. They have been found in chickens, both standard and bantams, guineas and coturnix quail.