Most Perfect Thing

''I think that, if required on pain of death to name instantly the most perfect thing in the universe, I should risk my fate on a bird''s egg''
Thomas Wentworth Higginson, 1862

How are eggs of different shapes made, and why are they the shape they are? When does the shell of an egg harden? Why do some eggs contain two yolks? How are the colours and patterns of an eggshell created, and why do they v...