Marshie is a creature (or, as he prefers, a monster) that lives on the 4 food groups of crisped rice cereal, marshmallows, syrup and butter. Somehow the chemistry reaction between those food groups made him look like a Rice Krispies square, or a marshmallow square, or a marshmallow treat, or whatever you like to call that sticky squishy square-shaped snack. You are what you eat, I guess.
He has big teeth, beady eyes, stubby marshmallow legs and gooey marshmallow hands. He is about 3 inches tall and he's probably as tall as he is wide, since he's kind of a square. Finally, he wants to let you know that he can snap, crackle and pop. He even made a video to demonstrate it.