The Land Worm is a rare enemy in Final Fantasy X, fought inside Sin after the point of no return. It is the only enemy, apart from the Monster Arena enemies and Dark Aeons, from which Dark Matter can be received, by way of a two million gil bribe. Land Worm is not required for the Arena and cannot be captured.
Land Worm's attacks are mainly physical. It will Headbutt one character for physical damage, and after suffering at least ten attacks it will Swallow a random character, removing them from the battlefield. Shortly after, it will Regurgitate the character, causing heavy damage and Delay. Its signature attack is Earthquake, which inflicts heavy magic-based damage. Land Worm takes one round to prepare for Earthquake, allowing the party to buff themselves or summon an aeon to negate the damage.