Facebook created a facial

In case we needed another reminder of Facebook's mass surveillance capabilities, we now know the company once built an app entirely for real-time facial recognition.

The social media giant experimented with a camera app that could identify people using Facebook's facial-recognition tech, according to a new report from Business Insider. The app was reportedly tested internally with Facebook employees between 2015 and 2016, and was "an example of future innovations" at the company.

According to BI, the app was fairly rudimentary, with a "basic camera interface" that could identify individuals and show their Facebook name and profile photo. You know, sort of like a dystopian version of Snapchat.

In a statement, a Facebook spokesperson said the app was never distributed outside of its own employees. And that those who were testing it could only use the app with other Facebook workers and existing Facebook friends who had facial recognition settings enabled on their account.

“As a way to learn about new technologies, our teams regularly build apps to use internally," the spokesperson said. "The app described here was only available to Facebook employees, and could only recognize employees and their friends who had face recognition enabled.”

Though BI reports the app hasn't been in use for years, the fact that Facebook created the app and showed it off as as an example of employee "innovation," underscores why Facebook's use of facial recognition has been so controversial. Facebook has more than 2 billion users, many of whom likely don't realize the company can store their biometric data. And even though it has so far only used facial recognition for photo tagging, the idea of its tech being deployed more widely is ... unsettling, to say the least.

And Facebook doesn't exactly have a great track record when it comes to user privacy. Which is why Facebook's use of facial-recognition technology has been widely criticized by officials and privacy advocates.

Earlier this year, the company finally changed its facial recognition settings to make it easier for users to opt-out of face-recognizing photo tags. That feature, which Facebook originally labeled "tag suggestions," is currently the subject of a multi-billion-dollar lawsuit, and has been called "deceptive" by the Federal Trade Commission.

Given that, it's not surprising the company opted to stop testing this particular internal app. But it's an important reminder that Facebook is very, very good at finding ever creepier ways of watching its billions of users, regardless of what Mark Zuckerberg says about privacy.