sea pen vs anthozoan

sea pen and anthozoan both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea pen	Yes	No	No	No
anthozoan	Yes	No	No	No

As nouns, anthozoan is a hypernym of sea pen; that is, anthozoan is a word with a broader meaning than sea pen:

sea pen: fleshy featherlike warm-water colonies
anthozoan: sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed

Other hypernyms of sea pen include actinozoan.

sea pen (noun)	anthozoan (noun)
fleshy featherlike warm-water colonies	sessile marine coelenterates including solitary and colonial polyps; the medusoid phase is entirely suppressed