alcyonarian
noun
al·cy·o·nar·ian ˌal-sē-ə-ˈner-ē-ən 
: any of a subclass (Alcyonaria) of colonial anthozoans (such as the sea pens) having polyps with eight branched tentacles and eight septa
Word History
Etymology
ultimately from Greek alkyoneion, a zoophyte, from neuter of alkyoneios of a kingfisher, from alkyon kingfisher; from its resemblance to a kingfisher's nest
First Known Use
1861, in the meaning defined above