"Narwhal and Jelly learn a thing or two about tusk-tooth dental hygiene . . . and feelings! Everyone knows that Narwhal is a big fan of sugary treats--but Jelly is shocked when Narwhal's tusk-tooth isn't looking so pearly white anymore. Thankfully, no one knows more about dental hygiene than Shark--he has seven rows of teeth, after all! Meanwhile, Jelly and Crab try to teach Narwhal that it's fine to frown if you're feeling down. Can Narwhal's friends...