A century egg, a hundred-yr-old egg? A preserved egg, a mysterious egg...
Usually eaten with some preserved ginger slices, in congee or as an ingredient for some Chinese dishes (I used it for Spinach soup)
Have you heard of it being preserved by horses' urine?
Anyway, decided to go do some research on the net how it's really being preserved.
Wikipedia's entry about century egg...
The traditional method takes 3 years for the egg to be ready for consumption!
The modern method takes a few weeks.
About the eggs being preserved in horses' urine, thankfully that's only a myth :)
Nevertheless, it's best not to take them often...
This site has some nice pictures of the century egg :)