“Without phosphorus there would be no thought,” observed Jacob Moleschott a 19th-century physiologist and philosopher. Phosphorus is one of the six main elements that make up the human body and an essential element for life as we know it for the creation of DNA, cell membranes, bones and teeth in humans, and even the microbiome of ocean-dwelling plankton–as a possible signature in the search for life in the cosmos. Unlike hydrogen, oxygen, carbon, nitrogen and calcium, phosphorus is rare. And it is even more scarce elsewhere in the Solar System. The source of its arrival on early Earth remains a mystery.