Unlocking Biology's Potential Understanding the extent of biodiversity is one of the greatest challenges. Decline in biodiversity poses dramatic consequences to almost every aspect of human development, either directly or indirectly: from food supply to global health, from climate change to economy. Our ability to respond to these threats depends on efficient and thorough exploration, classification, and interpretation of biodiversity. Some components of the biosphere are visible to the eye, such as plants and animals, and have obvious importance: we eat, drink, breathe, and also dress and build with plant and animal materials. But microorganisms, the invisible majority of living forms on planet Earth, remain mostly anonymous to us, even though this vast biota plays critical roles in regulating global-scale processes and driving essential nutrient cycles that support the trophic needs of all life forms, including plants and animals. Over decades, we have learned much by studying cultivable model microbes, but as field microbiology has demonstrated, cultivated microbes represent a small fraction of what really exists in nature. Therefore, cultivation represents a severe bottleneck to the study of most of the planet’s biodiversity, but techniques are being devised to overcome this obstacle. This session will illustrate the challenges of exploring microbial diversity in natural habitats such as the open oceans, deep into the ground, or inside our own bodies.