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PHILADELPHIA (CBS) — A retro favorite is returning to the Philadelphia Zoo. Zoo Keys are returning this spring, the zoo announced Wednesday.

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.

“While visiting Creatures of Habitat, guests can use the famous ZOO KEY at audio books located at each Lego brick sculpture as well as other areas throughout the Zoo. Visitors can unlock insider secrets and stories about the magnificent creatures living at Philadelphia Zoo, told by animal keepers who care for them,” according to the Philadelphia Zoo’s website.

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The Lego sculptures will be scattered throughout the zoo, each with secrets unlockable through the Zoo Keys.