Prince Harry and Meghan Markle’s firstborn turned one on May 6. The public rarely sees baby Archie, so it was a huge surprise when the Duke and Duchess of Sussex shared an adorable storytime video of their son on his first birthday.

Many have noted that Archie looked like his dad Prince Harry in the clip. But that’s not the only thing that fans noticed in the video.

Eagle-eyed supporters saw something on Archie’s book that sparked their curiosity. The front page of the book “Duck! Rabbit!” that Meghan Markle was reading to her son has a small blue sticker on it.

What made the mysterious sticker even more interesting is that it read “Archie’s Book Club.” Fans then took to Twitter to share their delight about their discovery.

"There’s a sticker on that book with 'Archie’s Book Club,’” one wrote. "I can’t deal with so much cuteness,” another one shared. “I am officially joining Archie's Book Club,” one fan noted. "Archie's Book Club. Where do I sign up?" another supporter commented.

Some speculated that the book may be a gift to Archie from Oprah Winfrey. The 66-year-old media executive, actress, talk show host, television producer, and philanthropist is known for her love for books and she also has a book club called “Oprah’s Book Club.”

"The book they’re reading could be a gift from Oprah,” one pointed out. “It has an 'Archie’s Book Club' sticker on the front and Oprah likes to give personalized 'book clubs' as a baby gift."

Meanwhile, it was previously speculated that Meghan Markle would follow Kate Middleton’s footsteps in marking Archie’s first birthday. The Duchess of Cambridge always shares new photos of her children to mark their special milestones. Recently, the wife of Prince William has shared snaps of Prince Louis, who turned two on April 23, and Princess Charlotte, who turned five on May 2.

Even though Prince Harry and Meghan Markle have turned their backs on royal life to live a “peaceful life” and have kept Archie out of the public eye, they were expected to share a photo of their little boy on his birthday. When fans asked if they would see Archie on his special day, a spokeswoman for the Duke and Duchess of Sussex said: “You can expect to see him.”

But Prince Harry and Meghan Markle shared more than just photos as they marked Archie’s birthday with a charming video.