The subclass Acnidosporidia comprises a group of single-celled parasitic organisms that infect a wide range of animals. Synonyms for Acnidosporidia include the class Myxozoa, the phylum Myxosporidia, or simply myxospores. These synonyms refer to the small, oval-shaped spores that are characteristic of these organisms. Myxozoa are known to cause several diseases in fish and other aquatic organisms, and have been studied extensively for their unique life cycles and intricate host-parasite interactions. While the name Acnidosporidia is commonly used in scientific literature, it is important to be aware of these alternative synonyms to fully appreciate the breadth of research on these fascinating organisms.