While actors can sometimes be stubborn and challenging, they are generally willing to take direction. James Ford Murphy, Pixar head of animation and the director of its new short Lava, had no such luxury when working with his lead character, a roughly three-mile-wide Hawaiian volcano named Uku.

“We struggled with it a lot,” Murphy tells Yahoo! “But I feel like, once we were able to embrace the limitations of it, it unlocked all sorts of possibilities. I love that about animation: You can really make a mountain come alive. You can’t do that in another medium.”

For Murphy, that meant giving Uku the feeling of movement by surrounding him with birds, dolphins, whales, clouds, and of course the lava, as well as making the camera swoop up and around him. It also meant telling Uku’s tale — a love story between two explosive rock formations — largely through music and his unique facial expressions.

To create the face of the mountain, Murphy used an amalgam of the faces of Kuana Torres Kahele, the musician who is the voice of the mountain; Honeymooners star Jackie Gleeson, and the bulldog in the Chuck Jones animated classic “Feed the Kitty,” which Murphy considers perhaps his all-time favorite cartoon. “That cartoon has so much heart and so much of the humor comes from genuine emotion,” he says. “That was a major inspiration for us.”

What inspired Murphy to make Lava was a love of the islands that took seed when seeing pictures of Hawaii as a kid growing up in Detroit — a sentiment that was cemented the first time he heard the late Israel Kamakawiwo’ole’s version of “Somewhere Over the Rainbow.” Says Murphy, “I thought that if I could marry the rich imagery and with the power and emotion of music, then I could really make something cool.”

Audiences can see Lava when it screens in front of Pixar’s next feature-length film, Inside Out, in theaters June of 2015