I'm not sure what that is but it is not a cud. Looks discolored and looks to also have been applied to it. Maybe paint.
+1 on nail polish. I used to use nail polish on my matchbox cars and coins all the time when I was young.
it was a cheap alternative to paint that was peeled off. I still have some matchbox/hotwheels around too that I nail polished, like a fire truck ... I'll have to take a looksie.
Not a cud as a cud is raised. Do a little research of cuds and you'll increase your understanding and knowledge very fast. It's damaged and it's worth a cent. Edited: to correct my spelling cuss my fingers are too fat for these little keys. Hehehe
I edited the cuss to cuds. Cuss the edit button was still active. Cuss I'm a nice guy and cuss I got you. Ok, I'll cussing now. Thanks again.