Thousands of these small plants were being flushed through the tiny, intertidal channels. They had a sharp, tought, spiny foot which was superb for latching onto rocks and sand. Some would then work their way into the sand as the water pulsed them back and forth. Each was about 60mm long.
Sublittoral zone, near the mouth of a large open bay. The bay is generally very shallow with clean sand floor but receives a decent flush of southern ocean water via some very deep channels.