Chaetomorpha antennina
Chaetomorpha antennina is a species of green algae of the family Cladophoraceae.
''Chaetomorpha antennina typically forms erect brush-like tufts of straight, rigid, unbranched filaments on surf-exposed intertidal to shallow subtidal rocky shores and attaches by rhizoids; however, under laboratory culture conditions the filaments may produce lateral branches, demonstrating morphological plasticity.''