Mountain #2 appears in "Memories of Boom Boom Mountain." She sits just behind the Mountain Man. When Finn decides to turn Mountain Man around so that he cannot see the Marauders roughhousing, Mountain #2 objects since she enjoys looking at Mountain Man's back, which she thinks is "gorgeous."
She has areas with grass and trees all over, and her whole body is green/gray-colored rock. She has grass on her head that resembles hair. Unlike Mountain Man's, her arms are very short.
No! Over here!... Don't turn him around! If you do, then I'll miss looking at his beautiful back! It's gorgeous!
And I can still see this gorgeous back!