Moss

From Muppet Wiki

Moss is a gray mouse who attends school and plays soccer with Tutter on Bear in the Big Blue House. Moss is introduced in the show's fourth season.

When Tutter starts attending Mouse School, he decides that he wants to be Moss's friend in the episode "Tutter Gathers Some Moss," but he isn't sure how to go about doing it. He tries doing and saying things to impress him, but they don't really work. He and the other kids of the Big Blue House sing a song titled "With a Friend Like Moss" about how great it would be if Tutter were Moss's friend.