GREENSBORO, North Carolina — Log onto Facebook, Twitter or Instagram and you won't have to scroll long to find blasts from the past.

Friends, family, and even celebrities are sharing what they looked like in 2009 and what they look like now in 2019.

It's called the "10 Year Challenge".

You might've also seen it as the "Glow Up Challenge" or the "How Hard Did Aging Hit You Challenge."

But before you join in, tech experts like Kent Meeker say not so fast.

He says social media giants could be using data from your photos to sell to third parties.

Others say Facebook who owns Instagram could be secretly mining data from the photos to improve its facial recognition algorithms.

That theory spread fast thanks to an op-ed published by Wired magazine.

The article is so popular, Facebook is now trying to distance itself from it saying it gains nothing from the challenge.

Facebook told CBS News," Facebook did not start this trend, and the meme uses photos that already exist on Facebook,"

That's true for those who do use old Facebook photos, but Meeker says by doing the challenge you're now dating your photos giving the year they were actually taken rather than uploaded. 

Meeker says it could be all fun and games, to show how much you've changed or stayed the same, but then again maybe not. He says at this point we will have to wait and see. 

The biggest message Meeker wants to pass along is always a relevant one. Be careful what you're sharing on social media.