Form in function is that something works so brilliantly well that despite its ugly appearance, people find the idea and functionality itself a kind of beauty.
Function in form is that despite something seems to be not functional at all, but because of its beautiful appearance it functions as an attraction or decoration. That is function in form.
Paradoxical things are not necessarily mutually exclusive. In fact you see interpenetration of dualistic concepts everywhere. The seed of evil in good, the seed of intelligence in stupidity.
I think this is nature's way of embedding change in systems. Planting the seed that so that the thing does not have an eternal property. so that change is the only constant.