In this atomic force microscope image, the color red indicates where a Shewanella oneidensis bacterium is expressing the protein OmcA in order to “breathe” the metallic mineral hematite. An oval marks the approximate location of the bacterium. OmcA is clearly present around the edges of the bacterium -- in the outer membrane -- and in an ooze surrounding the bacterium. Image courtesy of Brian Lower, Ohio State University.