A sedentary sea anemone gets attached to the lining of the hermit crab is a type of interaction in which one species is benefitted while the other is neither harmed nor benefited.
Such a type of relations in ecology is called commensalism.
Ectoparasitism is a form of parasitism where the parasite (ectoparasite) lives outside the body of the host.
Amensalism is a type of species interaction where one organism is affected but another organism gets harmed.