Made by an unknown potter.
The underside is black from a house fire.
I have thought of firing it just above 600 deg. c. to burn of the black organic reside, but so far lack the nerve or real need to.
Wood ash glaze.
I'm intrigued by my growing list of vessels made by forgotten potters. Perhaps the following book would be a good starting place of research for you; But I need an Australian ref. any suggestions?