User blog comment:Guardian Assassin/Theories, Fanon, and Other Absent-minded Ramblings: Part 2/@comment-3982778-20110515031353/@comment-3568630-20110516181524

Actually, it has now been confirmed that (as I suspected) they are *not* from space: http://www.gameinformer.com/b/features/archive/2011/05/13/ac-revelations-back-to-the-present.aspx?PostPageIndex=1