Slughorn's Hourglass

Horace Slughorn's hourglass is a clock made of two glass vessels connected with a narrow passage, with a green fluid flowing through inside and serpent design outside (represent him as a Slytherin member and former head of the house). Slughorn already own this object by the time that teenage Tom Riddle is studying at Hogwarts.

Appearances

 * Harry Potter and the Half-Blood Prince (film)