Plectaster decanus
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/47651201@N07">Tim Binns</a> from Tomahawk, Australia
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/wildroo/49733487091/">Mosaic Seastar</a>