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.
Rock Pens
Image courtesy of the NOAA Office of Ocean Exploration and Research, 2015 Hohonu Moana. Download larger version (jpg, 1.5 MB).

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.

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