Hydra Egg is the eighteenth optional quest. It can be obtained by talking to Jack at the Shipyard. The player is required to travel to the Central Islands and fight Hydras there. All hydras that are not born through another hydra have a 30% chance to drop the Hydra Egg, which must then be brought to Jack. Alternatively, the player can go to the Arena to fight hydras in the Island Cup and skip going to the Central Islands altogether. Returning the Hydra Egg to Jack will complete the quest and the player is rewarded with 700 EXP and Water Materia.
Five minutes after completing the quest, the player may return to Jack to have him comment on his newly hatched hydra.