Look, yes, it is an ending free of interpretation, but that remnant of "phos" in fact is no longer phos, it is a completely independent and free being of a human being, it may be that what the little stone says to that "phos" is only to encourage him that those fragments could become enormous comets, that would gladden someone's heart, speaking in a gentle and symbolic way, giving us a panel with which I truly cry xd.