Green feather algae (Caulerpa sertularioides) within a tide pool near the Hālona Blowhole on Oahu, Hawaii. Surrounding the C. sertularioides is a field of Scroll algae (Padina sp.).
<a href="//commons.wikimedia.org/wiki/User:Coughdrop12" title="User:Coughdrop12">Coughdrop12</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>