green boring sponge
... that the green boring sponge hollows out galleries in limestone rock?
... that the <b id="mwAbI"><a href="./Cliona_viridis" id="mwAbM" rel="mw:WikiLink" title="Cliona viridis">green boring sponge</a></b> hollows out galleries in <a href="./Limestone" id="mwAbQ" rel="mw:WikiLink" title="Limestone">limestone</a> rock?