
Protists, or microbial eukaryotes, play vital roles in various habitats, including aquatic and terrestrial environments as well as animal microbiomes. Their diverse range of relationships includes parasitic and commensal interactions, as well as free-living roles in driving nutrient cycles and stabilizing the biosphere. The ancestors to animals, fungi, and plants, were protists. As the most understudied yet phylogenetically diverse group of eukaryotic life, protists offer a wealth of opportunities to uncover novel biological processes, redefine fundamental aspects of cell biology, and address intriguing evolutionary questions.