In the world of microbiology, there’s an ongoing battle between different bacterial species competing for survival and dominance. However, under certain conditions, two species can actually thrive together in a dual-species biofilm. The cooperation between P. aeruginosa and S. aureus in cystic fibrosis leads to increased disease severity. But so far, only little is known about the chemical communication mechanisms between those bacteria. CSI:FingerID identifies a metabolite that could be related to the increased pathogenesis of this dual-species biofilm in cystic fibrosis.