Shields are weapons carried by Cobalts. They are the most visible part of a Cobalt, and they are their main weapon of defense. They did not appear in the movie as Cobalts weren't in the movie back then. They made their debut, along with the Cobalts themselves in the game where they are utilized by the giant, walking Blues as defense weapons. In Slush Tile Rush, they gain a more detailed design.
Slush Invaders: Game
Shields are used by Cobalts to protect Big Blue or any other enemy from the attacks of the Slush Fighters. When the Cobalts are destroyed, their shield rolls off. There are also shields in the background of Moon Prison, the 18th level of the game.
Slush Tile Rush
As the Cobalts make their return in Gildedguy's first ever mobile game, so do their shields, which have been surprisingly detailed, as they now have a bucket of Blue Paint sketched on it, along with a flask that seems to be full of Blue Paint, two Blues facing opposite directions and a centre Blue, who seems to be Big Blue. The Cobalts use their shield to create a tile which lasts for a limited amount of seconds.