I know from this (first image) piece that Boffo was known to have made some at least, of the design with these three spirals on.
Th most common shape is the "bullet bowl", I'm not absolutely sure of the dates. They were made (shortly) after Michael Harris left, I don't know if they were made during his time there, or if this is one of his designs.
I do have a bullet bowl I suspect was made by MH, but I could be wrong. (it's the one centre front in the second, group image.)