A lot of fungus.
It was described as “mint” by the seller in Japan.
To his credit, he has sent me a replacement lens. It’s not quite as nice cosmetically, but the glass is clean (other than dust, which all of these Mamiya RZ lenses seem to attract in great quantity).
Yet, I wonder if I should keep and pay for the eukaryotic-exotic first lens?
It seems to perform spectacularly.