Where does this piece come from?

[seapotato]

[TheOrcKing]

That is one of the Nixel faces from the new Mixels sets specifically this little bugger. Here's the other for future reference.

[seapotato]

Thanks! Does the face go on te mixel build?

[TheOrcKing]

Thanks! Does the face go on te mixel build?

It can if you want. The faces are originally meant for the little guy but being a 2x2 circle tile makes it easy to stick just about anywhere really.