Every animal must urinate to get rid of liquid waste in their body. While the pee of a healthy person has a distinctly yellow color, it’s been unclear to scientists for centuries what actually gives urine this hue. Now, a team from the University of Maryland and National Institutes of Health believe that they have solved this mystery by pinpointing the microbial enzyme that makes our pee yellow. The findings are detailed in a study published January 3 in the journal Nature Microbiology.