Apparently, a tractor was ploughing the earth and this turned up (~15 years ago), broken into many pieces (was glued together later). Here is a link to the album: https://imgur.com/a/vrRxm
Is it Ceramic ? It certainly does not look like pottery, the substance feels kind of "glassy". How old could it be ? What was it used for ?
I don't think it could be that old because it is too round and good-looking and symmetrical, I think the craftsmanship is too good for anything other than relatively modern. But, I want it to be as old as history!
You should consider posting this over at /r/whatisthisthing as it would be a more appropriate sub. Also consider providing more context in which the vessel was found (geographic location, how deep the tractor was plowing, whether anything else has been churned up over the years). As it stands, with no context, it is extremely difficult to provide an answer.