The Chronologicum is an hourglass that is able to manipulate Time in various methods. It initially belonged to Kraggler, who used it to drain youth out of Yin and Yang in the episode "Old School". After Kraggler's defeat, Yin managed to salvage and repair the Chronologicum with sellotape. When Yang is suspicious that someone is spying upon them, Yin and Yang use the Chronologicum to travel back in time and find out who the spy is. Yang only wants to use the Chronologicum to spy on Lina instead of spying on the spy who's been spying on them who is Coop since day one. Zarnot is also sent back in time, and magages to shatter the Chronologicum in the episode "Who Knows What Evil Lurks". In the episode "League of Evil", Yin and Yang discover that Master Yo had used the Chronologicum as a toilet roll in the outhouse. Apparently the device still works perfectly, despite it has been destroyed two times. In the end, they never found out who the spy was, but they did learn to trust each other and to work together Brother-Sister.