In the experiment, researchers exposed Pseudomonas aeruginosa to silver nitrate. David Anvir from the Hebrew University of Jerusalem says he and his colleagues observed the dead bacteria acting like sponges, soaking up silver. The dead bacteria were then introduced to a solution of living P. aeruginosa, and the zombies released their silver to achieve equilibrium, unleashing a microbial massacre. "It worked even better than our expectations," Anvir says. "It's a new, previously unrecognized mechanism of how an antibacterial agent kills."