Look carefully and you'll see an outline that should not be part of the reverse design. Let's keep the answer to ourselves until tomorrow so everyone has a chance to see it and guess.
Sorry, this one MIGHT have helped with the entire coin showing but this is the only unusual "added" design feature present.
Heck with it I'm going to tell, it's over a five-dollar bill. I'm smarter than the average bear. Sorry @Insider
This is a fairly strong die clash on a buffalo nickel. NORMALLY, the obverse will show letters from the motto under the indian's chin. This coin did not, making it unusual enough to take photos. UNFORTUNATELY, I've spent 10 min. looking for the other side to post and cannot find it. I didn't want to put the obverse image in the OP. I wanted to wait and use it in the answer. I get an "F" on this quiz.
There is a multi clash event. It would be cool to see the obv. And know what date it is. I searched to find a match and couldn't, with out maybe looking at some books. Neat coin. It would look good in my collection. LOL
A clash struck into the depths of the devices? I don't know the series but that's one helluv a clash if that's what it is!