My favorite scientific discovery is an often leaned-on pillar of microbiology: agar. The discovery of this invaluable resource is often credited to Robert Koch, while in reality, it was the wife of one of his associates, Fannie Hesse, who suggested its use. Fannie worked as an unpaid assistant for her husband in Koch’s lab and supported research by preparing environments for bacteria to grow in, cleaning equipment, and making illustrations for publications. As her husband and Koch struggled to find a growth medium that could overcome the limitations of gelatin, Fannie suggested using agar. When her husband notified Koch of the new technique, he immediately added it to his nutrient broths but made no mention of the Hesses’ vital contributions in his 1882 paper discussing the discovery. Agar is an indispensable tool in the microbiology laboratory, namely due to characteristics like the ability to withstand high temperatures and degradation by many microbes, among others. Without agar, we would not be able to perform critical procedures like streaking for isolation or making plate counts to determine dilutions. However, what makes this discovery my favorite is that it highlights the vital roles played by women throughout STEM fields and encourages conversations regarding the necessity of acknowledging these contributions. In my research of Fannie, I read sources that clarified how her illustrations were drawn so accurately that they supported a strong understanding of microbiology. I think that even the fact we would need evidence to prove Fannie really understood what she was doing illuminates the assumption of ignorance placed on many women. Overall, Fannie not only contributed a whole world of advancement and potential to the field of microbiology but did so while being disregarded on account of her gender; subsequently illuminating barriers faced by women in STEM fields even into the modern-day.