Microorganisms (Bacteria, Archaea, and viruses) are key mediators in nearly all of the planet’s elemental cycles. However, our understanding of the ecological roles of many groups of microbes has been hampered by low-resolution analytical approaches to studying the staggering diversity present in nature. As a result the tree of life is full of branches, which remain undiscovered, and those, which have only been identified in single-gene sequencing surveys. This is a fundamental gap in our understanding of biology. Filling in the genomic gaps in the tree of life will provide a rich context to understand the evolution of life on the planet and will provide us with a genetic understanding of how microbial communities drive biogeochemical cycles.