It turns out the Seaweedies are high in carotene and Arnold 's exclusive eating them has pigmented his skin .
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 Arnold 's skin .
The class has to learn about cells and how they get energy to solve the mystery before Arnold is forced to accept the award .