Generally organisms are green for one of two reasons: they use chlorophyll for photosynthesis, what the Phactor calls "really green", or they have a green-pigmented camouflage, which produces a pretty clear dichotomy between plants and animals. Down deep in the animal clade where you begin to get close to the never never land of unicellular organisms where distinctions like plant and animal do not work, you find some exceptions: green hydra, green clams, green sea slugs, green corals, and all of these harbor symbiotic algae in their bodies, but not in their cells. So of course once you get used to making such pronoucements, an exception pops up and forces you to go find the bloody thing in your book manuscript and add a dinged dang endnote! Algae are known to live within amphibian eggs in the "gell" surrounding the embryo, which might be considered intracellular, but maybe the Phactor misremembers something about amphibian eggs. The algal cells take up nitrogenous waste and get a nice wet habitat. But now the algal cells have been found inside a salamander embryo itself, the first truly cholophyll green vertebrate, although still lacking vertebrae at that stage of development. Does the embryo gain some benefit from the algal symbiont in addition to the removal of nitrogenous wastes? Does the algae share its photosyntetic products with the salamander? Maybe this will get those darned vertebrate physiologists to learn something about photosynthesis.