If that is* a lemon squeezer foot, then it's funny because I was only hearing about them for the first time last weekend. All I can say is apparently they COULD be an accessory (although that's probably not the right word) that could be bought by the hundred, and then used by different companys to complete their own style of cup or upper part. What I mean is, the foot could be made by a different company to the top. It was only when something like UV was used on complete pieces that it was discovered that they didn't necessarily start life as one unit.
*I couldn't identify a lemon squeezer base, as it's a new term I heard only during that conversation.
As far as I am aware, the big difference between a lemon squeezer and a normal star cut square base is that the lemon squeezer has a distinct domed cavity underneath.
I've always laughed at the name, as after all , if the cavity is designed to take a lemon, it would be peel side towards the glass, and what good would that be to squeeze it!!