PHILADELPHIA (CBS) — Zoo keys have returned to the Philadelphia Zoo after a 12-year absence, bringing back all sorts of nostalgia. The program started in the early 1960s.

There are 22 audio storybook boxes with educational information about animals situated throughout the zoo, including in front of the flamingos.

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Bird curator Ian Gereg recorded the message and heard it for the first time Thursday.

“I think it’s nice to give people that additional insight when they come to the zoo. Guests can put their key in the box and learn a little more about the animals maybe they didn’t know before.”

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Nine-year-old Wai Vong, of King Of Prussia, got his first zoo key.

“What I liked about it is instead of going up to somebody and talking to them about bears or something, we can just put a key in here,” said Wai.

There are boxes situated near 12 wildlife scenes throughout the zoo, featuring life-sized animal sculptures made out of Lego bricks.

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The Lego animals are part of the Creatures of Habitat exhibit running now through Sept. 30.