Old Dish

I have no idea whatsoever what this is. It belonged to my grandmother. She had it in her kitchen for as long as I can remember. The dish/container(?) is very heavy. It could be made of porcelain. The walls of the dish are very thick. My grandmother used it in her kitchen. Sometimes she kept lard in it and other times she used it for salt.
Any help would be greatly appreciated.

Thanks for looking:)