Zoothamnium niveum
... that the ciliate Zoothamnium niveum is so densely covered by symbiotic microbes that it appears white to the naked eye?
... that the <a href="./Ciliate" id="mwBtc" rel="mw:WikiLink" title="Ciliate">ciliate</a> <i id="mwBtg"><b id="mwBtk"><a href="./Zoothamnium_niveum" id="mwBto" rel="mw:WikiLink" title="Zoothamnium niveum">Zoothamnium niveum</a></b></i> is so densely covered by symbiotic microbes that it appears white to the naked eye?