Orginally made in China, the egg also made way to southeast Asia. It is made by preserving duck, chicken, or quail eggs in mixture of clay, ash, salt, lime, and rice hulls to fifty or a hundred years. Though, it can take several weeks and months. On the egg, there are snowflake/pine branches pattern on it and the yoke black. It can be eaten on it’s own, side dishes, in rice soup, etc.
And as a bonus….The pink eggs you often found in Thailand is Thousand Year old eggs.
It has an odor of sulfur and ammonia, which led some to believe these were soaking in horse urine. This is proven false, though still in Thailand and Laos, the name given to them literally meant “horse urine eggs.”(Thai & Lao: Khai yiao ma)
-(Laos admin, Oyo)