"Not to sound insane, but Apple Martin graduating high school is really making me feel the passage of time," one person tweeted.
"Apple Martin just graduated from high school, jeez, where did the time go?" another user shared.
"APPLE MARTIN GRADUATED HS?! i remember when the media went crazy cus they named her apple lol," one fan pointed out.
Paltrow occasionally posts updates about her children on Instagram.
On May 14, she posted a photo of Apple for her 18th birthday.
"18. I’m a bit of a loss for words this morning. I could not be more proud of the woman you are. You are everything I could have dreamed of and so much more. Proud doesn’t cover it, my heart swells with feelings I can’t put in to words. You are deeply extraordinary in every way. Happy birthday my darling girl," Paltrow wrote.
For International Women's Day, Paltrow posted a FaceTime screenshot featuring Apple. "Today I want to pay tribute to one (technically almost) woman on the cusp of it. This woman gives me hope for the future of sisterhood, and for the future of our planet. And this woman has made me the woman I am today more than anyone else," she wrote.
It's clear that Apple Martin has grown up right under the world's nose, and will likely go on to do big things.
As fan on Twitter said: "Manifesting the Apple Martin from privacy to it girl status pipeline."
Celebs Who Kept Their Children Away From the Public