Astaxanthin gives our sea kelp coral its color. Astaxanthin is similar to some pigments that give coral exoskeletons their color. This is not just a similarity in color but also in chemistry. Most corals obtain the majority of their energy and nutrients from photosynthetic unicellular algae, called zooxanthellae, that live within the coralís tissue, and these algae also produce pigments that protect the coral from the sun. Because of its particular molecular structure, astaxanthin serves as an extremely powerful antioxidant. It has a very effective quenching effect against singlet oxygen, a powerful scavenging ability for lipid and free radicals, and effectively breaks peroxide chain reactions. Carotenoids are effective at low oxygen concentrations, complementing the activity of vitamin E which is effective at higher oxygen concentrations. Astaxanthin has also been shown to enhance and modulate the immune system. The antioxidant and immunomodulating activities, in combination or separately, may reduce the acute inflammation reaction in the skin, and tissue just beneath the skin, that follows excessive exposure to UV radiation.