Earth was one of the four android creations of the Keeper. He had the ability to manipulate earth.
The Keeper was left by her makers on the Keeper's World to restore it after it was devastated in an ancient war. To assist with this task, and to fend of her loneliness, the Keeper created four nameless android helpers. One of these was an android in male form who could control earth, such as rocks and soil.
During the Battle of The Keeper's World the androids sided with Princess Leia Organa, Luke Skywalker, C-3PO, and R2-D2 against a squad of Imperial Stormtroopers. While demonstrating his powers, Earth covered R2-D2 with soil, frightening him. Later Earth caused a storm of rocks and boulders to fall from the underground caverns of the Keeper's Temple, distracting the Stormtroopers long enough for the Rebels to escape.
Earth had the appearance of a human male with orange hair. He was not immediately identifiable as a droid, save for his photoreceptors, which looked like a yellow light shining from black eye sockets.
Earth seemed to be the most impulsive of the Keeper's android creations. Upon first meeting the Rebels, he tersely demanded they identify themselves. Later, while demonstrating his powers, he covered R2-D2 in earth without thought to R2-D2's comfort, disturbing the droid. When this was pointed out to him he promptly apologized, showing that despite his impulsiveness he did mean well.
Through some unknown means Earth had complete mastery over his namesake element, controlling both dirt and rocks as he willed. He was able to finely control the earth, covering up R2-D2 in dirt without damaging the droid, as well as wield rocks and earth in combat to devastating effect.