Find the Main Idea in the passage
Sea Otters collect large hard-shelled abalones in their
teeth during dives to the sea bottom, then each picks
up a stone with its forepaws. Surfacing, the otters roll
onto their backs, place the abalones on their bellies,
and clasping a stone in both front feet, smash the
shells open. Therefore, Sea Otters use these stones
as hammers.