Several rock pens – a type of sea pen adapted to live on a hard bottom by modifying the peduncle (the large swollen structure at the base) into a form of suction-cup – grow alongside a precious pink coral, Pleurocorallium secundum, at 433 meters depth off the southwest tip of Ni’ihau. A neon blue fish, Epigonus glossodontusis, can be seen swimming past the lower edge of the Pleurocorallium.