Why is the walrus nicknamed “tooth walker”?

The walrus (Odobenus rosmarus) is a huge flippered marine mammal found in the Arctic Ocean and subarctic waters of the Northern Hemisphere, having a discontinuous distribution around the North Pole. The walrus's two tusks—actually two long, sharp teeth—help the cold-water species fight polar bears, defend itself from other walruses, and move across the ocean floor in pursuit of its preferred meal, clams. The "tooth walker" momentarily fixes itself to the ocean floor by digging its tusks into the muddy sand in search of food. It then retracts its tusks, walks forward, and continues the procedure.