Flatworm eyes and mitochondria

This is no empty statement: Science, especially biology never ceases to amaze me.  I was researching a couple of topics to talk to you guys about.  It has been a while since I’ve written a “sciency” post and I found the coolest thing!
Did you know that some flatworms use mitochondria to make optical lenses?
How about that? Exciting, eh? Eh?
Well?
Ok, I was floored; I find it very exciting at a personal level because it was totally unexpected, and I even wrote a book mostly about flatworms!

Credit: Dr. Kim Urban
What I find remarkable about it is that mitochondria are semi-independent entities in eukaryotic cells. They are kind of “cells within a cell” in a true sense. The current understanding of the function of mitochondria in eukaryotes is about the generation of adenosine triphosphate (ATP), the bioenergetic currency of all things biology.
Mitochondria and chloroplasts (these latter found only in photosynthesizing plants, algae and microorganisms) are thought to be symbionts that became interrelated to other cells billions of years ago. Among other things, this symbiotic relationship seems to be the key reason why true biological complexity can exist.

Credit: http://mysite.cherokee.k12.ga.us/personal/jennifer_forsyth
One can write a book about it and indeed somebody has, Dr. Nick Lane in his book “Power Sex Suicide Mitochondria meaning of life” explores the intriguing adventure of mitochondria in nature and tells their story in much better way that I could.
The thing that impressed me the most about the mitochondrial use in biological lens-making is how in our good Earth did evolution come up with this “idea”? (It is very difficult not to speak in a personifying way but keep in mind that evolution does not seem to have an explicit direction, at least under current paradigms). Even more remarkable it seems that this trick has been used by more than one class of flatworm, presumably through convergent evolution.
I am no evolutionary or developmental biologist; I have said elsewhere that I am a pharmacologist/neurobiologist with a tad of physics envy, so please do not take whatever I say about evolution or development as revealed truth. I can understand how tissues within an organism can adapt and develop a variety of functions in an organism. The thing is that mitochondria are separate entities, although truth be told, they are not truly independent from its host cell. Any comment from an appropriately trained colleague on this matter would be much appreciated.
I am trying to obtain some of the original papers that reported these facts so I can try and make sense of them and pass any insights to you, my faithful readers with the greatest taste in your choice of what blogs to read… You know? I am liking this convergent evolution thing more and more… Stay tuned!
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