Stuff on the reverse

What is the stuff on this otherwise nice looking coin and any suggestions onhow to remove it? It seems to be some kind of glue . 

Thanks 

Chuck

OOps forgot the pic

A picture would help us to see what you are looking at but I'm going to guess acetone.

Edit: Yes, looks like it was glued onto something at one time. I'd start with just water to see if it loosens it. If not then try the acetone.

Full sized picture.

Sound advice by our esteemed colleague. Only water and then acetone if needed because god only knows what that stuff is exactly.  Please hurry before somebody claims it to be a mint error! 

harryg

 

 Please hurry before somebody claims it to be a mint error! 

Hahaha, yes, that seems to be the trend. Although, it's not funny.