Hydroids are aquatic invertebrates that resemble small polyps. They can be found in both saltwater and freshwater environments, and they are known for their ability to filter feed from the water around them. There are many different synonyms for hydroids depending on the species and location in which they are found. Some popular alternatives to hydroids include hydrozoans, hydrozoids, and hydrozoa. Other synonyms for these fascinating creatures include hydromedusae, hydroid colonies, and hydroid polyps. Despite their small size, these creatures play an important role in the ocean ecosystem and are truly a wonder to behold.