Margaret's music box appears in the episode "Jake vs. Me-Mow." The music box belonged to Margaret, Finn and Jake's adoptive mother, who used the music box to sing a lullaby to lull Finn and Jake to sleep. After her passing, Finn continued to carry the music box around in his backpack.
The music box is brass-colored with a ratchet lever with a brown handle to operate it. The music cylinder sits on a bedplate between two dogs with outstretched arms (the two dogs could be Jake and his brother, Jermaine). The uppermost base is decorated with orange outlines of triangles, while the lowermost base is decorated with brown circles. Their paws glide along the cylinder's bumps to produce a musical sound.