The Halls of Time The Grim Adventures of Billy & Mandy : Season 2 Episode 23
TV-Y7-FV Cartoon Network 30m int(0)
Aired: August 1st, 2003 @ 8:30 PM EST on Cartoon Network
After missing on a school trip, Grim takes Billy, Mandy and Irwin to the "Halls of Time" for a tour. There, Billy and Irwin mess the hourglasses that symbolize each person's lifespan. When they leave, they accidentally leave their own hourglasses, including Grim's, upside down, resulting in the group getting younger as time passes. Grim allows the kids to disappear by going before birth, but he cannot restore his own hourglass to its correct position and he disappears too.