WHAT IS THIS? New description notes added since original post
This glass jar was found in Lake Washington last summer, at a section of Madison Beach where locals have been tossing their unwanted housewares for decades. Does anyone know what it is? It is about 3" wide and 2.5" tall. It is made of a single piece of glass and has threads on the rim for a screw-on cap or lid. The reservoir or whatever it is in the center is the same height as the outside jar, but the top is slightly irregular as if a close seal were not required. As you can see this reservoir or whatever it is is not quite cylindrical, but slightly flattened. I can't figure it out.