OOOOOOOO! Pretty!
Bit like a thought, idea, concept about anything really, only on a bigger scale. Where do they come from? What do they look like? How do they develop? What determines the result?
Personally, the end of 'Men In Black' tickles me, who's to say that's not how it is. Especially if thought really can become form, which man proves on a daily basis.
How's that?