Found this exploring a bottle dump. It was a glass block coin bank with the back broken off... obviously to get the coins. The embossing is amazing and regardless of its current state, it is certainly a keeper.
I dug one of these but the back was gone on mine. Your's was probably the Esso world's fair 1939 bank, that piece looks exactly like the back of that. The missing piece has the Esso logo on it. Unfortunately the only way you could get the money out of these was either carfully picking out the coins with a butter knife, or by breaking the bank open. Most owners figured that the latter of the two options was easiest.