Also known as the Ritteri Anemone or the Magnificent Anemone

Picture by Elizabeth Guck

The reason the domain is Eukarya, is it's more complex and includes genetic material that is organized into a membrane bound nucleus.
The kingdom Animalia is described as multi-cellular organisms that can respond to its environment.
Being in the phylum Cnidaria tells us it is a primitive animal that has a single body cavity.  This cavity doubles as its stomach, lungs, intestine, and circulatory system.
The class Anthozoa is for sea anemones and hard and soft corals because they are attached to firm objects.
Then you can narrow down the order Actiniaria, which is  the order for all sea anemones.
The family Stichodactylidae includes two genus, Heteractis and Stichodactyla, both of which host anemonefish.
The genus Heteractis is known for it's stinging tentacles which look as though they have bubbles on the ends.