Hard to tell.
Including Protheans and Forerunners
and Mass Relays and Rings (LOL)
Edit: Precursors too...
Edit 2: ALL OF THE STUFFS IN THE UNIVERSES EVEN TREES
[Edited on 03.25.2012 2:43 PM PDT]
-
I call bull-blam!- on crucible, there is not even a basic explanation as to how it makes things synthetic. Either way, Forerunner could [i]shift the axis of a [b]galaxy[/b][/i] Their tech is lightyears ahead of anything Mass Effect (probably because the Reapers wouldn't allow it) and the Precursors were beyond that.