Katy Perry looks unrecognizable in new fresh-faced photo that sparks reaction

Katy Perry has shocked fans by posting a throwback to her younger days on Instagram.

The Dark Horse and California Gurls singer posted the photograph, which shows her as a fresh-faced 21-year-old ready to party at a roller skating rink, to her socials on Sunday in order to celebrate American Idol's 21st birthday.

Find out why Katy believes this season of American Idol is the best yet in the video below.

WATCH: Katy Perry introduces American Idol season 21

Fans of the Teenage Dream singer songwriter rushed to comment on Katy's almost unrecognisable appearance in the photo from her early adult life.

"Fetus Katy!" one joked, surprised at the throwback picture.

DISCOVER: Katy Perry, Lionel Richie, Ryan Seacrest's and more American Idol stars' stunning homes

"You looked so cute at 21!" another added.

Meanwhile a third person commented: "Always been gorgeous."

Katy's Instagram throwback

Several fans also left red heart emojis and teary-eyed faces in reply to the cute photo.

Katy captioned her post: "[American Idol] is celebrating its 21st bday this year. When I turned 21 I rented a roller skating rink and had McDonald’s 'cater' along [with] 2 kegs in the middle of the rink…"

MORE: Katy Perry left extremely emotional during raw American Idol moment

The Bon Appetit singer, who is engaged to Pirates of the Caribbean star Orlando Bloom, continued: "Two friends broke bones but we had a lot of fun," although she then added in parentheses: "So I was told, idk I had just turned 21."

Katy and her fellow American Idol stars

The now 38-year-old star finished her post with a challenge to fans: "Anyway watch #idol rn and let me know what YOU did for your 21st (that you can remember) in the comments," she wrote.

Numerous followers responded to the singer's request for their own stories by adding their own, which ranged from birthdays celebrated quietly at home during the pandemic to stories of exciting nights out, bar crawls, and even one arrest.

SEE: Katy Perry and Orlando Bloom celebrate daughter Daisy's second birthday and the photo is too cute

But others simply couldn't get over Katy's own story. "Umm you need to write a song about this night," said one person, echoing others' argument that the A-lister's 21st sounded like it would make an amazing sequel to her hit single Last Friday Night (T.G.I.F.).

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