Century eggs

[Leonidas]

Hello,
I‘m living in China and they sell everywhere „Century Eggs“ which are duck eggs, covered whth soil, salt and rice hulls. They are left to “ripen” for a few weeks before being sold. Do you know if they are truly fermented or just cured, the difference being fermented = many bacteria and enzymes, cured = less water and maybe changed chemical composition. Maybe it’s a combination of both. I can’t speak Chinese (yet) so I can’t ask anyone here. Maybe one of you know more about this. Thanks!