serpent eel
... that the serpent eel wriggles backwards into the sandy seabed, leaving only its head visible?
... that the <b id="mwAsI"><a href="./Serpent_eel" id="mwAsM" rel="mw:WikiLink" title="Serpent eel">serpent eel</a></b> <i id="mwAsQ">(example pictured)</i> wriggles backwards into the sandy seabed, leaving only its head visible?