What is a "narwhal"?

A narwhal is a medium-sized toothed whale found in Arctic waters, easily recognizable by its long, spiral tusk protruding from its upper jaw, which is actually an elongated tooth. The tusk can grow up to several meters in length and is believed to be primarily used for mating rituals and as a sensory organ. Narwhals are social creatures that travel in groups called pods and are well-adapted to life in icy environments.