Clementines from Morocco, like the Mandarins from Arizona, sometimes come to western Canada, but seldom. The clementines are juicy, but seeds are common. The Chinese and Japanese are almost seedless; I remember seeds were more common back in the 1950's-1960's.

I don't know when the word 'zipperskin' appeared. The trick is to remove the skin in one piece, with no punctures to the segments.