six-holed keyhole urchin
... that the slots in the test of the six-holed keyhole urchin may help prevent it from being washed away by the current?
... that the slots in the <a href="./Test_(biology)" id="mwAks" rel="mw:WikiLink" title="Test (biology)">test</a> of the <b id="mwAkw"><a href="./Leodia_sexiesperforata" id="mwAk0" rel="mw:WikiLink" title="Leodia sexiesperforata">six-holed keyhole urchin</a></b> may help prevent it from being washed away by the current?