* Cnidarians: Many cnidarian species, such as corals, develop symbiotic relationships with single-celled algae called zooxanthellae. This symbiosis is crucial for the survival and growth of coral reefs. * Fungi: Fungi are known to form various symbiotic relationships with other organisms, including * Mycorrhizal associations with plant roots, where the fungus helps the plant absorb nutrients in exchange for carbohydrates. * Lichens are a symbiotic relationship between a fungus and an algae or cyanobacteria. * Protozoa: Some protozoa living in the digestive tracts of termites and ruminant animals, helping them break down cellulose. Therefore, all three groups - cnidarians, fungi, and protozoa - have species that can form symbiotic relationships with other organisms.