Tetrahymanol is primarily used as a biomarker in geochemical studies to assess past environmental conditions. It is especially valuable in identifying the presence of ancient microbial communities in sedimentary rocks and petroleum deposits. Due to its stability over geological time scales, it helps researchers trace the evolution of microbial ecosystems, particularly those involving anaerobic conditions such as in freshwater or saline environments. Its presence in sediments often indicates inputs from specific protists or bacteria, making it a useful tool in paleoenvironmental reconstruction. Additionally, tetrahymanol derivatives are studied for their potential in understanding early eukaryotic life and biogeochemical cycles in ancient Earth history.