Exotic duck egg

We have an exotic duck egg that is boiled. But there are 2 types of boiled duck egg that is sold by the ambulant vendor with a basket. One is the plain boiled egg that is like a bigger chicken egg that is hard boiled. Another is the Balut which is exotic and is a challenge for foreigners. Why so? That duck egg is half-hatched and has an embryo inside. It is traditionally a healthy food for athletes.

The Balut and the plain boiled duck eggs are still available but from the ambulant vendors. Much more, they are usually sold at night only.