[LargeFormat] Fungus

[philip lambert]

I just bought unseen a wideangle lens and it arrived today having what
appears to be a deposit of wool on the outer surface of the rear glass that
withstands conventional lens cleaning materials.
I assume this is fungus. It is quite obvious, more so with a loupe.
Does anybody have an effective metod of cleaning this off and is the glass
left with a surface mark?
Does a cleaned off fungus return?

At the moment the lens is enjoying some strong sun on the window ledge prior
to be returned to vendor for a refund..
Philip