Antique Clay Gallon Jug

I found this jug in 1986 while on a diving job in Lake Maurepas, Pass Manchac, Louisiana. Locals claimed that there was once an old Spanish fort within a few hundred yards from where I found it. Also, previous divers brought up 60 eight-pound cannon balls. I have been looking and haven't found anything like it on the web. Does anyone know if it is Spanish, French or North American Indian? It should be 18th century. No one that I have shown it to has seen one like it. Leonard Charrier the treasure who found the Tunica Indian Treasures looked it over once and felt it was probably Spanish. He had found hundreds of intact pottery and said it resembled nothing like he had found.