In their recently published Science paper (reprint) Brett Baker and Jill Banfield and prior members of the Banfield group (Gene Tyson, Eric Allen, Judith Flanagan, Phil Hugenholtz), in collaboration with Rick Webb (Univeristy of Queensland), describe the discovery microbes on a novel branch on the tree of life. The archaeal organisms grow within acid mine drainage microbial communities that play a key role in metal sulfide mineral dissolution and acid mine drainage formation. These groups, named ARMAN, were overlooked by conventional microbiological methods (PCR and culturing). Surprisingly, these cells appear to be among the smallest yet described. The study shows how community genomic analyses can detect new lineages of organisms and facilitate their characterization, enhancing our understanding of the role of microorganisms in important geochemical processes.