This green plantlike creature is actually an animal with algae plants living inside it. In this symbiotic relationship, the algae gain protection from snails and other grazers and don't have to compete for living space, while the anemones gain extra nourishment from the algae in their guts. Contrary to popular opinion, this anemone’s green color is produced by the animal itself, not the algae that it eats. Giant green anemones are often solitary and exhibit aggressive territorial defense against rival anemones; in some locations, however, there can be up to 14 green anemones per three square feet.
Some fishes develop resistance to the giant green anemone’s sting by covering themselves with mucus.