How can we reconcile the noble Hadith: "Allah has sent down no disease except that He has sent down a cure for it, except death" (and in some narrations "old age"), with the fact that jellyfish can renew their life cycle and return to the egg stage when they become old, which means they do not die from old age?

The prophetic Hadith states: "Treat yourselves, O servants of Allah, for Allah has not created a disease without creating a cure for it, except old age." This Hadith clarifies that seeking treatment does not contradict reliance on Allah. Then, it explains what is known about jellyfish of the species Turritopsis dohrnii during their maturation stage, where their cells decompose and then reassemble to develop new jellyfish in the polyp stage. There is no evidence that this state is without death; rather, it is death followed by a return to life, by the permission of Allah, resembling the life cycle of a plant. This is not true immortality, but rather a new life cycle where the second iteration relies on something from the first. The BBC report on this matter mentioned the word "death" twice, which confirms that it is a life cycle punctuated by death.