Well for one they were torn apart from their place on the temple in order to ship them to England. Illegally.
They were acid washed a few years ago removing their patina, about 1000 years worth of damage.
Anything else?
one of the ships sank and a one section was left underwater for a YEARS, recovered and then left on an salt water beach for more YEARS, until elgin could raise more more for his ill gotten booty.