Have they ever left? In a way, they’re different than they were in the first few games.
Crystals (クリスタル, Kurisutaru?), also called orbs and spheres, are legendary and often elemental objects that have appeared in every game in the main Final Fantasy series. Even in games where they are not a central plot point, there has been at least some reference to them. Crystals often have power over natural phenomena, and function as a powerful source of magical energy. Many antagonists focus their efforts on seizing the crystals to gain power towards their goal.
For the first five games, the tradition crystals have made appearance as elemental
The original set up was to have four elemental crystals: a Water Crystal, a Fire Crystal, a Wind Crystal, and an Earth Crystal. On occasion crystals may be aligned with Darkness. Crystals are often found in crystal rooms in early games. The crystals are often treasured for their power and many myths and legends surround the true extent of their abilities. Uncovering the truth of these myths and their meaning is a typical part of a Final Fantasy game.
But sometime after Final Fantasy V, the crystals have taken on a new form. In Final Fantasy VI and VII, they’re a product of biological lifeforms. In Final Fantasy VIII, they’re pillars, like the rooms in Final Fantasy II, III, IV, and V. They make a comeback in Final Fantasy IX. Then they crystals return to their non-traditional status of crystalline objects. This continues from Final Fantasy X all the way until Final Fantasy XV, when they appear again.
So what are the crystals going to look like in Final Fantasy XVI and beyond?
Should they even be traditional in later series?