Daphnia pulex, known more commonly as the water flea, is barely perceptible to the naked eye but plays a vital role in freshwater ecosystems around the world as prey to both vertebrate and invertebrate species. Water fleas also keep algae blooms (which can cause millions of dollars in damage to the U.S. economy) in check. But outside its watery habitat, this minuscule crustacean similarly leaves an outsized legacy in the world of science.