purple scallop sponge
... that the purple scallop sponge has a mutualistic relationship with the mollusc on which it lives?
... that the <b id="mwBYw"><a href="./Mycale_adhaerens" id="mwBY0" rel="mw:WikiLink" title="Mycale adhaerens">purple scallop sponge</a></b> has a <a href="./Mutualism_(biology)" id="mwBY4" rel="mw:WikiLink" title="Mutualism (biology)">mutualistic relationship</a> with the mollusc on which it lives?