Mountain Morg is a giant creature at least 10 feet tall made out of moss from a cave on Mt. Gabel. It is relatively humanoid in appearance and walks upright on two legs, which are relatively stout compared to its arms which hang low enough for its fingers to touch the ground. Mountain Morg does not have a neck and instead its head is a small lump attached to his torso. His mouth is wide and large (probably to accommodate its large appetite) and his eyes are small yellow dots spread far apart.
Mountain Morg is a carefree spirit that loves to walk around in its cave and eat moss all day, having a gluttonous appetite. It is a very gentle creature, but it will not hesitate to defend itself and kill anything that appears a threat to its well-being.
It is not known just how old exactly the Mountain Morg spirit is. It could be relatively young or as old as the earth itself. It is only known that Mountain Morg has been observed by at least one person long enough for him to know Mountain Morg's temperament.
"Okay! Follow me. This road leads up to the summit of the mountain. You'll find a cave at the summit. There's a spirit called the Mountain Morg that lives there. He's usually very gentle, but he'll try to kill anything that attacks him. I know it sounds a bit barbaric, but you're going to attack him. You will find yourself fighting for your life. I'm sure of it. I'll wait here with Maya."
—Kazan instructing Lang to attack the Mountain Morg so as to awaken his Origin.
Mountain Morg is encountered by Lang within his cave after Kazan instructs his new pupil to enter it and provoke him. The reason for this is to find himself in a near-death situation that will awaken the power of the Origin inside him. Lang is amazed at the size of Mountain Morg, but draws his sword in preparation to attack. Mountain Morg stops eating moss off a cave wall and turns around to see Lang with his sword drawn out, which causes him to attack the young swordsman. Lang is unable to harm Mountain Morg with his physical attacks and gets mercilessly pummeled to the ground.
Just as Mountain Morg prepares to give the finishing blow, Lang's origin awakens and repels Mountain Morg's punch with a ball of fire that shields him. Lang gets back up with revitalized power and summons his Origin, Galea, to attack Mountain Morg. The Mountain Morg becomes enveloped in a ball of fire and is destroyed. It is later discovered that Mountain Morg restores itself after apparent death as it is seen walking around its cave eating moss off the cave walls.
Mountain Morg has an enormous body made entirely out of moss. Its size and weight are so immense that it causes small tremors with every step it takes. In addition to it being able to execute powerful attacks with its great strength, it is also able to completely absorb all physical attack damage due to its moss body. Because Mountain Morg is a spirit, it cannot truly die. If it is destroyed it will reconstitute itself from the moss in its cave.