>>6341144Sorry for the wait anon, had to wait to dig them out of the trash.
It's not super impressive looking, but I assure you that's plastic mold. I noticed the luigi from the american reproductions line I had did the same thing but, guess I didn't notice it happened to the others.
The only causality was a shitty old toy island knuckles I got when I was like, 8 I think. Which I probably can/will clean with bleach.