I want to roll it in with Dense Flesh, because Dense Flesh by itself doesn't seem as worth its price tag as Regeneration, Immunity, or Durability. Dense Flesh compliments those three, but isn't so much worth it as a stand-alone Mega-Edge, and we all think Slow Aging isn't worth the price, so...why not roll them together?

My justification for it is that "dense flesh" can also be organ redundancy: The nova's body having reserve parts to take over for damaged organs, slowing down the shutdown of the nova's body due to injury. Such redundancy can also slow the aging process...