The article by Locey and Lennon investigates the scaling laws that underpin biodiversity, focusing on both microorganisms and macroscopic plants and animals. They compile a global dataset of approximately 35,000 sites and 5.6 × 10^16 species, including high-throughput molecular data and plant and animal community data. The study reveals that similar rates of scaling in commonness and rarity occur across microorganisms and macroscopic organisms, challenging the notion that scaling laws developed for plants and animals do not apply to microorganisms. A universal dominance scaling law is identified, which holds across 30 orders of magnitude and accurately predicts the abundance of dominant ocean bacteria. Combining this scaling law with the lognormal model of biodiversity, the authors estimate that Earth is home to over 1 trillion microbial species. The findings suggest that microbial biodiversity is greater than previously thought but can be predicted from the smallest to the largest microbiome, highlighting the need for continued research to catalog Earth's microbial diversity.The article by Locey and Lennon investigates the scaling laws that underpin biodiversity, focusing on both microorganisms and macroscopic plants and animals. They compile a global dataset of approximately 35,000 sites and 5.6 × 10^16 species, including high-throughput molecular data and plant and animal community data. The study reveals that similar rates of scaling in commonness and rarity occur across microorganisms and macroscopic organisms, challenging the notion that scaling laws developed for plants and animals do not apply to microorganisms. A universal dominance scaling law is identified, which holds across 30 orders of magnitude and accurately predicts the abundance of dominant ocean bacteria. Combining this scaling law with the lognormal model of biodiversity, the authors estimate that Earth is home to over 1 trillion microbial species. The findings suggest that microbial biodiversity is greater than previously thought but can be predicted from the smallest to the largest microbiome, highlighting the need for continued research to catalog Earth's microbial diversity.