Interesting, I must have seen hundreads ? of them because there are plenty around here in the homeland of Humppila. All I have ever seen have been with a plain base. Either with a signature or not.
However, now I googled and found another one with a patterned base, slightly different (?) from tradera - the Swedish "ebay".
I only wonder if Humppila sold/licensed the design or made them a little different for export as otherwise they look very much the same as the largest version of this known Revontulet bowl. (i.e. with a larger diameter across the base, there are 2 heights of bowls with a smaller diameter which however seem to be made with the exactly same mold if the pattern of the sides are compared.)