Answer to Fairday's Riddle: Unicorn of the Sea

Excellent guessing, Riddlers! This week we're swimming with the unicorn of the sea. Tune in Monday to find out how the answer ties into the children's picture book Margo's picked out for us. See you all around the book block. ~F

Mystery lore speaks of me— lines spell under the sea. I enchant Arctic coasts and have a tooth my blessing boasts. 

What am I? Answer: Narwhal
Shark Dance FEAR NOT THE UNEXPECTED