Waterfall of Xeno Blood

Waterfall Tangent: The SJ did us a favor and cleaned-up the Earth a few times so we (humans) their most prized creation could flourish. They shipped earlier deadly / viscous life back to the planet shown in Prometheus and entombed it for safe keeping and further experiments/improvements for a better suited place or to be picked/transported further into space at a later time. These entombed creatures would like their Earth and a home back. They have their own hieroglyphics telling their side of the story shown changing on the walls? The dark sphere shaped ship over the waterfall is a flash back to the dark sphere ship dumping Xeno goo cleaned up from Earth onto the planet in Prometheus. It is a waterfall/ river of dumped / recycled Xeno blood. Side question - why are there no plants / flowers on these planets?