The Lava Worm, also known as the Grey W in the Nintendo Entertainment System version, is an enemy in the original Final Fantasy. It is the weakest of the Worm family , distinguished by its green skin. It is weak to Ice. A normal Ice spell should be enough to kill it, and if it does not die, the player can finish it off easily. Due to the Lava Worm's reappearance in the "Marilith Room" of the Chaos Shrine, these enemies should not pose a threat to the player's party and can be easily defeated with a strong physical attack.
The Lava Worm also appears guarding chests in Gurgu Volcano, for example, guarding a chest in the large room in the second floor, in the section where there are a number of chests; and guarding the left-hand side of a chest in B4 (one of the chests in the room that is north of the entrance to the floor).