Arnold is about to have the honor of being the first kid to receive one of the Rocky Awards at the annual Granite Awards. However, he has an embarrassing predicament. For reasons that are never exactly explained, Arnold has eaten only Seaweedies for a month and has consequently turned orange. ("It's my favorite color; except when it's my own skin.") He then asks, "What's the difference between my skin and say, Phoebe's?" So, of course, the class goes on a field trip to compare their skin, but they get nowhere since none of Phoebe's cells are orange. The class has to learn about cells and how they get energy to solve the mystery before Arnold is forced to accept the award. It turns out the Seaweedies are high in carotene and Arnold's exclusive eating them has pigmented his skin.