The Full Metal Shell is a Sea Turtle. Only appeared in the Darius Twin game.
The first thing Full Metal Shell does on seeing you is launching little turtles from the top and bottom of his carapace. Perfectly destructible, but try and concentrate on his head, the only real weak spot of his. And when his turtle-launchers retract, fly above him. Otherwise, during the next attack, he literally sticks his head out to ram you and shoot six vertical lasers, up and down. There is enough space between them to sit, but ideally, you're better off staying either in line with his head if there's enough space or above him and bombing/shooting the hell out of him.When his head retarcts, he typically moves in a northwesterly floaty diagonal (try not to get rammed here too) and shoots five-bullet arcs. He then returns to his turtle-launching mode. If the vertical-laser attack doesn't give you too many nightmares, you should wrap it up eventually.