Wee egg

[MissChick@dee]

Have you cracked it open?

 

[aart]

Welcome to BYC!!
Probably just a glitch....

Fairy, fart, wind, rooster eggs are usually from a tiny piece of tissue breaking loose from the reproductive tract, or an immature ova(yolk) and the body forms an egg around it. Color can be darker than 'normal' as the pigment coating released has to cover a much smaller area so is thicker. Can happen with any age layer, but more common with new or older layers.
You and your daughter might enjoy this video: