iOS 11 public beta has been available since June, but there are still surprise features cropping up, including a newly spotted one that temporarily disables Touch ID.
Unearthed by a Twitter user and confirmed by The Verge, the feature is activated when you rapidly press the power button five times.
This pulls up the option to place an emergency call (the Emergency SOS feature), but it also locks up Touch ID. The finger-reading sensor won't work again until you input your passcode.
The security feature appears limited to the iPhone, at least right now.
As a refresher, Touch ID works by scanning your fingerprint to unlock your iPhone or iPad. It's a quick way to access your device without typing in your personalized pin.
However, there are times you may want to quickly and discretely disable Touch ID, and current methods take time. The most straightforward way up until this discovery was to turn off Touch ID in Settings, which requires multiple steps and looking at your device.
Pertinent to all this is that Apple is expected to introduce facial recognition in the iPhone 8. So-called Face ID may replace or be in addition to Touch ID, so having a way to rapidly disable these unlocking measures with a few subtle taps could be a welcome security feature.
We'll likely find out much more about what Apple has planned for the future of device security next month during the anticipated iPhone 8 launch event.