Unusual type of the Œ or Ö ligature, with a little E In the O. From an inscription while in the crypt of Cologne (Köln) Cathedral. Historically[when?] O-diaeresis was prepared as an o with two dots above the letter. https://crithitceramics.com/crafting-unique-campaigns-exploring-non-traditional-themes-for-your-next-adventure/