The Tubular Balgae replaced its ancestor the Cylinder Balgae. The Cylindar Balgae sank to the bottom of the river and now grow in hollow tubular stalks. It has grown even larger with many more cells. Its whole outside collects sunlight using photosynthesis. Since so many grow at the bottom it makes the river bottom look black like a carpet of oil or tar.
Living Relatives (click to show/hide)
None found. Note that this does not necessarily mean it has no living relatives at all, but that, assuming all taxonomy is filled in, its entire phylum is extinct; any relatives it does have likely do not resemble it.