Walrus

The walrus—or Odobenus rosmarus, literally the "tooth-walking sea horse"—is known for its ivory tusks. By hooking these tusks into ice floes, walruses haul themselves from the water. They also display these teeth to intimidate and joust for territory.

Walrus herds can contain thousands of walruses piled onto ice platforms and seasonally on beaches. They spend most of their lives at sea, migrating with the ice. Walruses pile on top of each other even if there's room to spread out.