Earlier quoted context omitted.
If you preserve the egg in lime, ash, and a few other ingredients for long enough, the egg turns into a "Century Egg" with an almost jello like look and consistency https://en.wikipedia.org/wiki/Century_egg Tastes kinda gross though (but I might be biased)
Weird that you mentioned it today. I just made one for the first time today after visiting the Chinese supermarket (I am not East Asian). Century egg is definitely one of the weirdest smelling things I have ever eaten. It smells like H2S. Took me back to my chemistry lab sessions.
I cant recall that much of my high school organic chemistry but I would think that H2S would be a degradation product of spoilt eggs