Vintage RRP Co. blue spongeware two-piece dip chiller.

This is a very unique piece. The bottom is meant to be filled with ice and the top is for your dip. This is a piece of pottery made in the USA (Roseville, Ohio). No visible cracks, chips or scratches in either of the pieces. Could be used as it was originally intended, or as two separate pieces. This would be an awesome addition to your Spongeware collection or just the piece to start your collection either for use or just for looks!! Not sure but I think may be from 50s, 60s.