Board Thread:Warhammer 40k General Discussion/@comment-211.26.90.118-20130728064425/@comment-8257990-20130807001021

Ah my Halo knowledge must be lacking then... I thought some of the Precursors turned themselves into some sort of dust like substance, which was origionally injected into those dog type things by the origional humans, this dust was corrupted over time and became the Flood.

That's how I thought it went from what I know...