However, in common with many mutualisms, there is more than one aspect to it: in the anemonefish-anemone mutualism, waste ammonia from the fish feeds the symbiotic algae that are found in the anemone's tentacles (Porat & Chadwick-Furman, 2004; Porat & Chadwick-Furman, 2005). Therefore, what appears to be a service-service mutualism in fact has a service-resource component.

Mutualistic relationships can be thought of as a form of "biological barter" (Ollerton, 2016). For example, in mycorrhizal associations between plant roots and fungi, with the plant providing food resources (ie, carbohydrates) to the fungus in return for other important nutrients (eg, nitrogen and phosphorous). Other examples include rhizobia bacteria that fix nitrogen for leguminous plants (family Fabaceae) in return for energy-containing carbohydrates (Denison & Kiers, 2004).