The order Cydippidea is a group of small, marine creatures with spherical or ovoid bodies that are covered in cilia. They are commonly known as comb jellies, due to the rows of cilia that run along their bodies, which they use for locomotion. The order Cydippidea includes several species, such as the sea walnut and Venus' girdle. While the term "order Cydippidea" is commonly used to refer to this group of creatures, there are several synonyms that can also be used, including the order Ctenophora, the phylum Ctenophora, and the comb jellies. Each of these terms is often used in scientific literature to describe these unique and fascinating creatures.