| any of several colonial coelenterates of the genus Pennatula and related genera, having the shape of a fleshy feather. |
| sea pen n. Any of various marine anthozoans of the families Stylatulidae and Funiculinidae, resembling and related to the sea feathers. [From its resemblance to a quill pen.] |
sea pen
any of the 300 species of the order Pennatulacea, colonial invertebrate marine animals of the class Anthozoa (phylum Cnidaria). The name sea pen derives from their resemblance to quill pens. They occur in shallow and deep waters from polar seas to the tropics.
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