Blooms of the seaweed sargassum have significantly increased in frequency and extent over the past decade in the Atlantic Ocean, and this pervasive growth is expected to continue. Abnormally large amounts of this brown alga washing up on beaches can harm local organisms, the coastal economy, and even human health. Algae often rely on the microorganisms living on their surface, or their microbiome, to obtain nutrients and other resources needed for their survival, meaning that a better understanding of the sargassum microbiome could help scientists develop new strategies to reduce its impacts. Recently, a team of researchers used genetic sequencing techniques to compare the sargassum microbiome with microbes in the surrounding seawater. They found that 28% of the DNA from the sargassum-associated bacteria was composed of viral genes, compared to just 0.02% in the seawater. Remarkably, the integrated viral genes direct biofilm formation and other functions affecting the bacteria-sargassum symbiosis, and further experiments showed removing these genes reduced the ability of the bacteria to form biofilms on the algal surface. These findings suggest that virus-mediated interactions may strengthen beneficial relationships between sargassum and bacteria, suggesting they could serve as a target for developing new methods to manage its explosive growth.