Years ago, Master Wu placed the Earth Dragon in the Caves of Despair to guard of the Scythe of Quakes. The scythe was placed in the dragon's mouth, presumably being what put him into a deep slumber.
Many years later, the Earth Dragon was awoken when four ninja, Kai, Jay, Cole, and Zane, removed the Scythe from his mouth. He scared off Samukai's skeleton army and then proceeded to assault the ninja in order to protect the weapon. Kai ended up using the Scythe to cause a cave-in, bringing down rocks on the dragon's head. This only served to slow the beast down, but the ninja were still able to escape.
Cole eventually returned and managed to befriend Rocky, using him as a ride in order to cross over to the Underworld to recapture the weapons. Later, Rocky flew the Earth Ninja to the Four Weapons Blacksmith.
Following the defeat of the Skulkin and the disappearance of Lord Garmadon, the ninja took to racing their dragons in their spare time. In one such race, Cole flew Rocky through a forest, using his bulk to simply smash through the trees that Jay's Lightning Dragon had to weave around. In the final stretch, with all the dragons neck-and-neck, Cole revealed his trump card: by dangling a roasted chicken in front of Rocky's nose, Cole motivated him to accelerate long enough to take the lead and end up winning the race.
At some point, dragon pens were carved into the mountain underneath the Monastery of Spinjitzu and Rocky began living there under the care of the ninja.
When the ninja learned that Lord Garmadon had apparently returned, Cole mounted Rocky and flew him to Jamanakai Village, racing the other ninja along the way. After the threat had been discovered to be merely Lloyd Garmadon, Cole flew Rocky back to the monastery. When the Hypnobrai attacked the village later in the day, Cole once again used Rocky as transport there.
After the Postman delivered Rocky's favorite treat—liver and toads—to Cole, the Black Ninja visited the dragon pen to feed it to his pet.
The next day while the ninja were out destroying Lloyd's treehouse fortress, the Hypnobrai attacked the Monastery and burned it to the ground. Due to being locked in his pen, Rocky was helpless to escape the flames until Cole returned and set him free. Rocky continued to accompany the ninja as they wandered the desert homeless, but once the ninja discovered the Destiny's Bounty, he settled down in some ruins nearby.
In need of heading to the Spirit Coves to molt their scales, Rocky and the rest of the dragons would bid farewell to the ninja, flying off. Later, the four of them would metamorphize and fuse into the Ultra Dragon.
Rocky has very rocky skin, so much so that he could camouflage himself as a pile of rocks with ease. He has large brown wings with holes in them and a spiked tail.
In the set 2509 Earth Dragon Defense, he has no wings but instead has a green frill around his neck. He is one of two dragons whose forelegs are separate from his wings, the other being the Lightning Dragon. He is the only dragon with a different head mold from all of the others.
- Rocky lacks wings in his LEGO set appearance despite him having wings in the TV show.
- He has a different head shape than the other Dragons.
- He is the only Golden Weapon Guardian Dragon to not have arms in set form.
- He was the first Dragon that was encountered.
- He appeared in LEGO Battles: Ninjago as a Goliath Battle Mode boss.
- He is a boss in Spinjitzu Smash!.
- Cole is very close to Rocky, more than Jay, Kai, and Zane are to Wisp, Flame, and Shard.
- He resembles the Elemental Earth Dragon.
- One of Rocky's abilities is spewing rock-slides and dirt out of his mouth.
- This is Cole's first Dragon, the second being the Elemental Earth Dragon. The latter's design seems to be based on that of Rocky.
- Rocky is very strong, as he is shown to be able to knock over a tree mid-flight and still keep going. (Shown in "Flight of the Dragon Ninja")
- Rocky's favorite foods are liver and toads, stated in "Home."