"In the ... ninth book of this ... graphic novel series, 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...