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"On each eye, normally an inconspicuous black spot, I found a tiny spherical lens perfectly situated above their light-sensitive cells"
"by accumulating refractive proteins, packing together, and becoming enlarged, these mitochondria have become lenses that focus ambient light onto the light-sensitive cells."
"What are we to think of this spotty distribution of mitochondrial eyes in the flatworm tree of life? ...Another possibility, however, is that this represents a convergence – unrelated lineages of flatworms may have all found a way to build lenses with mitochondria, just as dolphins, sharks, and ichthyosaurs all independently became streamlined for drag reduction in the water."
"Some dinoflagellates, single-celled photosynthesizers of the shallow ocean, have found a way to make lenses of their photosynthetic plastids"