Animal biology is fascinating for its incredible diversity in life strategies. These strategies amaze scientists and can also fire the enthusiasm of science students. One group of animals impressive in this way is the phylum "Cnidaria," containing some 10,000 invertebrate species that include jellyfish, corals, sea anemones, hydroids, and siphonophores. Many students have seen the flower-like anemones living on rocks at tide pools. The starlet sea anemone, "Nematostella vectensis," is found in estuarine salt marshes on both coasts of North America and southern England. Scientists use it to study many aspects of cnidarian biology from population dynamics to cell and molecular biology. Students can collect "Nematostella" from mud flats, rear it in the classroom, feed it, and spawn it year-round to obtain embryos. "Nematostella" adapts to the changing temperature and salinity of the salt marsh environment, so it is tolerant of less-than-ideal culturing conditions, such as those in a school science lab. In this article, the authors describe how to care for "Nematostella" and provide sample experiments. Students can easily design and carry out their own investigations into "Nematostella" biology, promoting authentic, student-directed research.