No a 100 year old egg is not really 100 years old.
In reality a 100 year old egg is just 100 days old and not 100 years old.
A 100 year old egg is just a name for an egg that is cured for 100 days.
The term 100 year old egg is just a misnomer because they are only cured for 100 days because eggs that would be cured for 100 years would be very bad to eat.
That is a long time for something to cure.
So if you eat a 100 year old egg you're really just eating an egg that was cured for only 100 days and not 100 years.