7. Century Egg
These aged eggs are rarely 100 years old but they could be anything from a few weeks to a few months old. Typically a Chinese dish, the eggs are preserved using a mixture of clay, lime, ash and rice hulls. The lime juice stops the eggs from spoiling but the most drastic change after three months of preservation is the colour. The yolk turns a dark green colour and the white of the egg turns translucent and brown.