Codium fragile is a medium green to dark green alga which consists of long finger-like branches with soft surfaces. It has various names, such as green sea fingers, sea stag horn, and oyster thief. It is called Cheonggak in Korean, meaning green antlers. This seaweed grows dangling or hanging down from the rocks on rocky shores. The interesting fact is the whole body is one cell. In some coastal areas of Korea, dried C. fragile is made into a traditional food, Kimchi. In Japan, it has been eaten for a long time for food and medicine to treat enterobiasis, dropsy, and dysuria. C. fragile extracts have been reported in many research studies to have diverse pharmacological activities, including anti-edema, anti-allergic, anti-inflammatory, anti-protozoal, and anti-mycobacterial effects. In human keratinocytes, HaCaT cells, non-polar fractions of C. fragile extract and a single compound, cholesterol isolated from C. fragile extract for medicinal purposes, inhibited UVB-induced inflammatory responses, including the increased expression of COX-2, iNOS, and TNF-α. Those extracts attenuated UVB-mediated oxidative damages such as lipid peroxidation and protein oxidation by regulating anti-oxidant on  BALB/c mice.