The decorated Easter Egg is common to members of the Russian Orthodox and Ukranian Orthodox Churches. The practice is common in the western provinces of Canada and in the northern tier of the United states where many Ukranians settled. There are books on the methods. The contents of the eggs are removed through tiny holes at the top and base of the egg. The surface is painted in very complex designs, incorporating religious symbols. Some take days to do and are highly sought for by collectors.
Surprised that the Fabergé jeweled eggs made for wealthy Russians and Ukranians have not been mentioned.
The practice seems to go back to the origins of the Orthodox churches. Some of the decorators use pre-Christian pagan designs.