Corrosion
noun, verbal noun
ふしょく
腐敗 （ふはい） Decomposition, Rotting, Corruption
腐食 （ふしょく） Corrosion
侵食 （しんしょく） Erosion, Corrosion
Corrosion should make you think of rot 腐 -chemicals eating 食 away at something.
The fool ふ was shocked しょく by the Corrosion even though the item was 100 years old.