Item from harry-potter-prisoner-of-azkaban by
A tiny golden hourglass on a long chain that turns back time one hour per rotation, loaned to Hermione by the Ministry to attend overlapping classes and used to save Sirius Black and Buckbeak the Hippogriff.
The Time-Turner is the most dangerous magical object the Ministry casually loans to overachieving thirteen-year-olds. Hermione used it throughout her third year to attend every elective simultaneously, arriving at overlapping classes by living extra hours and never telling anyone except McGonagall. The strain nearly broke her — she's exhausted, irritable, and occasionally flickers in and out of existence between classes. The real crisis comes when Dumbledore tells Harry and Hermione to use it to travel back three hours, save Buckbeak from execution, and rescue Sirius Black from the Dementor's Kiss — all without being seen by their past selves, because time travel operates on a closed loop where everything you do in the past already happened. The stag Patronus Harry sees saving him from across the lake isn't his father — it's his future self, three hours later, casting the spell he's already seen work. The Time-Turner makes Prisoner of Azkaban's finale a masterwork of circular narrative, and Hermione returns it to McGonagall afterward, having decided that living extra hours every day is not worth the cost.
A miniature golden hourglass hung on a fine gold chain long enough to loop around two people's necks. The hourglass is no larger than a walnut. Sand inside glows faintly. Each full rotation turns the user back one hour in time.
Also known as: Time-Turner, the Time-Turner, time turner