I was having a discussion with a friend last night about some lore-related stuff and I was wondering where I could look up some information on this.

The primals and where they come from was the topic. I was led to believe that the primals (or the ability to summon them) was brought about by the Agrius crashing into the Silvertear and releasing a seal or something along those lines that the primals were locked behind and the location was the Crystal Tower? I remember seeing the primals (I believe) in the opening cut scene for 1.0, but I could be wrong on all this. Do you know of any lore related things about this where we can get some information on this topic? This isn't some life or death Kirk vs. Picard discussion, but we're really interested in what has happened and the origin of some of the primals.