In Fullmetal Alchemist the door in the Truth realm has a huge symbol with all kinds of things on it:
I've seen the opening of Neon Genesis Evangelion today and noticed that the same symbol is shown in the beginning of the opening around 0:10 - 0:13.
I first thought that it was just a random symbol in FMA, but now that I've seen it in the opening of NGE, I believe that it must come from something else since there is no connection between those anime.
What is this symbol, where does it come from and what does it describe?
Here is a more detailed picture of the symbol: