Spirit Monsters are colored grey, originally as a rule, could not be Special Summoned, and are sent back to the owner's hand during the End Phase of the turn they are Normal Summoned, Flip Summoned, or flipped face-up. This also happens if they wound up in the opponent's hand via effects like Exchange. However, new Spirits have been released in The Duelist Genesis, one of which can be Special Summoned for a cost. Spirit Monster Cards are designated by having "Spirit" in the place where "Effect" would be.