Power Ztar

The Power Ztar (or Shadow Star) is an anomalous collectible that usually replaces the Power Stars found in regular gameplay, but it can replace the Metal Cap on rare occasions. Ztars take the appearance of a regular Power Star, but black with angry white eyes. The Ztars can either give a star or take away one, the latter being how it functions in Mario Party. When it replaces the Metal Cap, it acts very similar to the Starman from the original Super Mario Bros. When Mario collects the power-up, he turns pitch-black and invincible. The regular blue boxes turn black when this anomaly is present. They allegedly have been from an earlier build of the original Super Mario 64, though this is unknown.