blue moon?...

...or an Auracanas blue egg which mysteriously appeared on my verandah.

The blue colouring comes from the pigment oocyanin a by product of bile production and while brown eggs are white on the inner shell while the blue goes all the way through.

And yes there ar green eggs, laid by the brilliantly named Easter Eggers and Olive Eggers...I wonder if they were an inspiration for Dr Seuss?