(Purple eggs sold side by side with normal eggs in a market in the Philippines.)
They weren’t laid by some exotic bird. These are actually salted duck eggs. A popular preparation method involves dipping and curing the eggs in a mixture of clay, salt and water for two weeks.
The salted eggs are then cleaned and boiled, and sold in the market pre-cooked. They are colored purple to distinguish them from normal raw eggs.
Traditionally consumed for breakfast, they have apparently found their way into Southeast Asian recipes and even desserts!
Not that they were wanting attention to begin with!