Sapphire Weapon

Sapphire Weapon is an enemy in Final Fantasy VII. It is one of the five Weapons created by the Planet and summoned to protect it following the arrival of Meteor. It seems to be aquatic and can shoot a laser from its mouth. The Sapphire Weapon is the only Weapon that cannot be fought by the party at some point during the game.

Story
After Meteor was summoned and Tifa awoke in Junon, Heidegger reports to Rufus that a Weapon is approaching from the sea. When Sapphire Weapon finally reaches the shore, it arises from the water and rears its head in front of the city, only to have it blown off by the Junon Cannon.

It leaves a large crater underwater where it fell, and it is there that Emerald Weapon can be found after acquiring the Submarine.