I have done ayahuasca and many people report seeing something like this: http://pbmo.files.wordpress.com/2010/06/machine-elf-2.jpg I can say from my personal experience, that this is only one possible "hallucination" although quite common.

> it's not a "valid" trip unless you do You can definitely have a life-changing experience without encountering machine elves.

Feels like now that I've seen it, it could become a self fulfilling prophecy