01-22-2019 06:17 PM
01-22-2019 07:09 PM
01-22-2019 07:18 PM
That doesn't look like a mark. I"m not sure what that is or if you will ever figure out who made it.
01-25-2019 03:41 PM
IMHO, That is a mark.
Many potters use a "chop" mark which is stamped into the "greenware" / unfired clay. That mark often includes their initials or that of the pottery. I suspect this is a cojoined "UB". I didn't find anything with that chop mark on some of the studio pottery sites.