Birds eggs

[fraserjim]

How do Birds Eggs get the patterns on them ? some look as though they have been spray painted or paint applied by 'flinging'

[wildwood]

It's the earliest form of Bubble Jet Printing!

The patterns are laid down by pustules-like formations in the oviduct, which derive their pigment from body waste from the kidneys etc. At the latest stage of the egg's journey through the oviduct it is rotated through muscular movement, causing the steaked pattern on some species' eggs.
The patterns are obviously designed to assist in camouflage and shore-nesting bird-eggs are extremely hard to see until you are nearly on top of them. Birds that usually nest in rock-holes, covered nests, tree trunks etc. don't need the camouflage and lay white or slighly tinted eggs without decorations.