Balut is what it is called. A high protein delicacy enjoyed by Asians and others.
Fertilized eggs are kept warm in the sun and stored in baskets to retain warmth. After nine days, the eggs are held to a light to reveal the embryo inside. Approximately eight days later the balut are ready to be cooked, sold, and eaten. Vendors sell cooked balut from buckets of sand (used to retain warmth) accompanied by small packets of salt. Uncooked balut are rarely sold in Southeast Asia. In the United States, Asian markets occasionally carry uncooked balut eggs. The cooking process is identical to that of hard-boiled chicken eggs, and baluts are eaten while still warm.
Underaged balut with visible chickDuck eggs that are not properly developed after nine to twelve days are sold as penoy, which look, smell and taste similar to a regular hard-boiled egg. In Filipino cuisine, these are occasionally beaten and fried, similar to scrambled eggs, and served with a vinegar dip.
The age of the egg before it can be cooked is a matter of local preference. In the Philippines, the ideal balut is 17 days old, at which point it is said to be balut sa puti ("wrapped in white"). The chick inside is not old enough to show its beak, feathers or claws, and the bones are undeveloped. The Vietnamese often prefer their balut mature from 19 days up to 21 days, when the chick is old enough to be recognizable as a baby duck and has bones that will be firm but tender when cooked.
http://en.wikipedia.org/wiki/Balut_(egg)
Shelled and fried is one way to eat them.....
