Most people think of mushrooms when they hear the word “fungi,” yet most fungi do not produce them. There are an estimated 3 to 13 million fungal species on Earth, many of which are tiny in size.They can be found in a variety of settings, including soils, rainforest leaf tissues, and deep oceans. According to a new review published in the Annual Review of Ecology, Evolution, and Systematics, understanding how fungi migrate over a range of spatial scales is vital for understanding ecosystems and has consequences for agriculture and human health.