Holospira
... that the internal column (columella) of the shell of snail Holospira is hollow?
... that the internal column (<a href="./Columella_(gastropod)" id="mwArw" rel="mw:WikiLink" title="Columella (gastropod)">columella</a>) of the <a href="./Gastropod_shell" id="mwAr0" rel="mw:WikiLink" title="Gastropod shell">shell</a> of snail <i id="mwAr4"><b id="mwAr8"><a href="./Holospira" id="mwAsA" rel="mw:WikiLink" title="Holospira">Holospira</a></b></i> is hollow?