Though not fully seen, they are depicted as having red eyes that glow in the dark cave they live in, and that at least one has two giant purple arms with pointy fingers.
In Sugar Rush, Lightbulb discovered a cave that she believes will have heaps of candy. Once inside, she and Marshmallow walk though until multiple pairs of red eyes belonging to the monsters appear and scare them out. Lightbulb escapes, but Marshmallow trips at the entrance of the cave, and is dragged back in by one of the monster's purple arms. Later, Marshmallow is dropped out of the cave, with many bite-marks, but with a bag filled with candy (supposedly as an apology).