purple sea urchin
... that spines of the purple sea urchin provide shelter for large-headed Goby juveniles?
... that spines of the <b id="mwDUI"><a href="./Paracentrotus_lividus" id="mwDUM" rel="mw:WikiLink" title="Paracentrotus lividus">purple sea urchin</a></b> <i id="mwDUQ">(pictured)</i> provide shelter for <a class="mw-redirect" href="./Large-headed_Goby" id="mwDUU" rel="mw:WikiLink" title="Large-headed Goby">large-headed Goby</a> juveniles?