I am up for all scientifically sound speculations, and sources are highly welcome. I've looked into this quite a bit myself via scholar.google, the wiki article, and /r/askscience.

I'm really looking for more speculation about physical details of the organism, its environment, and its immediate ancestors.

e.g. How did they (referring to the LUCA and some immediate ancestors) acquire nutrients? What forms of mobility were available to them? How long was it until photosynthesizing organisms emerged?

mods: If this is too open-ended or too speculative, please let me know where I can redirect this question.

  • $\begingroup$ As far as I have read LUCA is just predicted to have certain characteristics. It is not physically found. You can have a look at this paper. It is about energy metabolism in LUCA. $\endgroup$ – WYSIWYG Oct 14 '14 at 4:33