It looks like a magic trick: Cells at the bottom of a liquid medium begin levitating, then hovering at a particular height. With no physical contact, an invisible force directs certain cells to float up or down in unison, like mini-submarines.

Researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab), UC Irvine, and the University of Illinois Urbana-Champaign (UIUC), have used biology to convert human urine into a valuable product. The team genetically modified yeast to take the elements present in urine and create hydroxyapatite—a calcium and phosphorus-based mineral naturally produced by humans and other animals to build bones and teeth.