Hello Marcus,
I imagine that is very possible. In naval warefare, there was Greek fire that was contained in vessels. In maritime/pirate tradition, there were stink pots, which contained foul-smelling weeds, animal dung, sulfur, etc, and made to shatter and spray on impact! (lovely to get hit with the rank stuff-
).
I'm hoping that perhaps the material mine is made from might shed some light on what nationality, era, or area of design. I know it's crazy, but the reason I asked about Spanish colonials and if they had grenadoes is because the pottery material mine is made from reminds me of Pueblo Indian pottery- that black, brittle clay from the American Southwest. Anyway, jst thinking aloud!