Final answer:
The narwhal is a marine mammal with a long tusk and distinct characteristics such as tail fins, dark body color, and a hammer-shaped head.
Step-by-step explanation:
The narwhal is a marine mammal known for its unique tusk that can grow up to 10 feet long. It has tail fins that extend horizontally from its body, and its tail is about half the length of its body. The narwhal has a dark body with coloring that is similar to the killer whale's, but it is larger in size. Its head is shaped like a hammer, and it has a single tusk.
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