The Thousand Year Old Egg is also called the Century Egg and is a Chinese delicacy.
It is an egg (duck, chicken or quail) that is "preserved" in a special mixture of clay, ash, salt, quicklime and rice hulls. I have heard that these can be stored for weeks or months.
Like the Balut, this is incredibly difficult for westerners to stomach. Unlike Balut, I have tried this and it is a taste I did not like. Just thinking about it makes me gag.