The Garnet Orb
Summoning Sailor Saturn herself (manga/second anime)
Unlike the other two Talismans that were sealed within the Pure Hearts of Sailor Uranus and Sailor Neptune, the orb was a mystical item which Sailor Pluto wielded on top of the immensely strong and powerful Garnet Rod she wields.
Sailor Pluto was able to use the power of the Orb to pull the other Talismans from their respective Pure Hearts, which meant Sailor Uranus and Neptune were able to remain alive once they were removed. Apart from being a part of the Garnet Rod, the Garnet Orb didn't serve another purpose other than to summon the Holy Grail.
As with the manga, the Garnet Orb serves as the third and final talisman for summoning the tenth and last Sailor Senshi of the deathly planet of silence: Sailor Saturn herself.
In the manga all of the three Talismans were in the possession of their owners, Sailors Uranus, Neptune, and Sailor Pluto, and once the mighty Holy Grail appeared they allowed for Usagi to transform and evolved into her much more powerful Super Sailor form as Super Sailor Moon. However, the main function of the Talismans was to call upon Sailor Saturn herself, as they did after the Silver Millennium fell into ruin and at the end of the Infinity arc. The orb also allowed Sailor Pluto to use the Garnet Ball and Chronos Typhoon attacks.