A retro favorite is returning to the Philadelphia Zoo! The zoo announced Wednesday that the iconic “Zoo Keys” are returning this Spring! Visitors can use their Zoo Keys on the zoo’s upcoming Creatures of Habit exhibit — life-size recreations of 30 animals made completely out of LEGOs. The LEGO sculptures will be scattered throughout the zoo, each with secrets unlockable through the Zoo Keys. If you don’t remember, the small plastic keys are shaped like different types of animals — they were in use from the 1960s (!!!) to the early 2000s. They’ll be coming back this April, so make sure to dig out your old ones too!