sea moss

from the GNU version of the Collaborative International Dictionary of English.

• (Zoöl.) Any branched marine bryozoan resembling moss.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any branched marine bryozoan resembling moss.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any of various red algae having graceful rose to purple fronds (e.g. dulse or carrageen)
• noun sessile aquatic animal forming mossy colonies of small polyps each having a curved or circular ridge bearing tentacles; attach to stones or seaweed and reproduce by budding