Nematomorpha is a phylum of elongated, thread-like organisms known as horsehair worms. Synonyms for Nematomorpha include Gordiacea, Nematoidea and Nematrema. These worms are found in both freshwater and marine environments and have a parasitic lifestyle. Their larvae infect various insects and arthropods and manipulate their behavior to ensure they are eaten by the host's natural predator, allowing the worm to complete its life cycle. Despite their strange and fascinating biology, horsehair worms are not well-known or studied by the general public. However, they have become a popular subject for natural history enthusiasts and have even been featured in documentaries and popular science books.