/ Thesaurus / S Synonyms of sea pen Find synonyms for: Noun1. sea pen, anthozoan, actinozoanusage: fleshy featherlike warm-water coloniesWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: loathe Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language