A pesky plankton discovers the secret to being a mussel in Fenske's salute to learning when to clam up.In minimalist, underwater artwork, a plankton drifts along. The shrimplike creature encounters a mussel, this one a rather sinister-looking bivalve, and says, "Why, hello, Mister Mussel!" Mussel twitches not a muscle. Plankton gets its cilia up. Plankton starts a lecture. "Let me tell you how this works," it says, a comment that ensures a disgruntled audience. "Let's say we give this another whirl, okay?" That's pushing it, clearly, but it also will gradually dawn on readers that there may be something to Mussel's silence. It is rendered with what passes for an underbite for a mussel, a feature that combines with its impassively scowling eyes to give it the look of an old-time cartoon gangster. In panels and full-page spreads colored in a matte palette, Plankton nags, beseeches, then notices a small opening in Mussel's shell. Getting closer and closer to hear better, finally pesky Plankton enters the breach and: "SNAP!" Exit one plankton, thankfully. As for Mussel: "Delicioso!" Perfect. That little rattle of Spanish is ideal. Then, in an instance where Fenske should have kept his clam shut, the final page serves up an ameliorative: the plankton pries open the mussel's shell and gets the last word: "AHA! I KNEW you could talk!" An enjoyable comeuppance. Just don't turn the last page. (Picture book. 3-5) Copyright Kirkus Reviews, used with permission.