Originally Posted by
Lunair
Oh wait. I went back just to check, and she WASN'T noted to be a rock, rather "an embodiment of pure ruination". The exact line is on page 200 of Encyclopaedia Eorzea Vol 3, and reads;
"Ultima, the High Seraph"
"So named for her ability to wield the ultimate form of destructive magic, the High Seraph was once nothing more than an embodiment of pure ruination. Yet, over time, the terror in which people held her shifted to reverence, and by a process not unlike the prayer-fueled creation of a primal, this worship quickened within Ultima a sense of self-awareness."
This directly suggests that she's only achieved the level of self awareness we see due to the collective beliefs of those aware of her. That said, what "an embodiment of pure ruination" actually translates to is vague as hell.