Nearly every environment on Earth is dominated by “microbial dark matter,” according to researchers from the University of Tennessee, Knoxville (UTK). Scientists use this term to describe all of the microbes that have never been grown in a lab culture, either because of a lack of knowledge or an inability to produce the right conditions. Their existence poses a problem, because to learn about microbes and their role in the environment, you need to be able to culture them. “Calling uncultured microbes “dark matter” borrows from astronomical dark matter, since both have been found to be ubiquitous, yet neither have been adequately characterized,” Karen Lloyd of UTK’s Department of Microbiology told Newsweek.