The Ooze is a gelatinous antagonist in the "Elmo the Musical" segment, "Karate Master the Musical."
The Ooze destroys all the shapes in an animal village. Karate Mater Elmo brings him to the Octagon area, which he also wrecks. When questioned about his motives, the Ooze sings a tearful ballad explaining his hatred of shapes - he dislikes shapes because he doesn't have one himself. Elmo makes some shapes for him to fit into, allowing him to be any shape he wishes. He now loves shapes and dubs Elmo the greatest shape expert in the world.