Quote Originally Posted by Zeromus_X View Post
If those annoying stat-orbs in the Mysidian Tower...can count, then
Aside from the one in the center that contains Ultima, there are four of them, and specific comments about wind, water, earth, and fire connected to them. It's not really a stretch of any kind.

I'd say FFVII's Crystal equivalents are the four Huge Materia.