It is definitely within girl angle just not sure whether that part at the end is stacking or not that's why I thought they might know more on Ingender, it took me a while to get a good amount of responses there too. If you change your title asking for lovemy4, Kirsty, mea and Aussie you may get a few more, they're the ones that really seem to know a bit more on the nub theory as well.
I don't believe the skull theory either and have looked into it a little last time as I didn't have a nub picture and I think that it really is just a myth.