There should be 2 different kinds of "scary face".
One is just showing the transformation from the head you are using to the scary face, which you can see "?"/"!" when using it.
Another one is changing your head temporarily to scary face, which you can walk while wearing the scary face.
How much do the two kinds of scary face worth in shells INDIVIDUALLY?
P.S. If you know, please tell me where the people got it? Maybe from auctions which are long time ago? (I know it is a rare.)