The Mogma are a new race in Skyward Sword who live around Eldin Volcano. Their appearance is a kind of cross between a prairie dog and an ape, and they are skilled diggers. Each Mogma has a unique hairstyle. When Mogma speak with Link, they pop the top half of their bodies out of the ground and usually go back under after they are done.
The Mogma appear to be a friendly race that helps Link, allowing Link to keep a Bomb Bag that he originally got for them, and warning Link about shady characters clad in red. The passion of all Mogmas is to search for treasure and can often be seen looking for treasure in dungeons. They also give Link the Digging Mitts. At some point around the volcano area, two Mogma are seen talking about a key for the nearby Earth Temple. They say that it was broken into five pieces and scattered across the area. Link must then use dowsing to locate the five pieces in order to get inside the temple.
While Link is looking for Sacred Water for Faron in the Skyview Temple, there is a Mogma looking for treasure. He realizes later on that there is just water in the Skyview Spring. He loses a Small Key that Link can later find, and he hints at the Goddess Wall nearby.
In the Fire Sanctuary, Link has to save a number of Mogma, similarly to how he saves Gorons in the Fire Temple in Ocarina of Time. One can be seen hanging from the ceiling by a chain. It is unclear why and how they were trapped.