When you smile, frown, or sneer at the iPhone X, the phone’s facial sensors can create expressive 3D emojis that mimic your very own face.

These dynamic 3D emojis are called “animojis,” and they're part of Apple’s foray into facial recognition and sensing technology. The new iPhone X is also capable of recognizing a user’s face using an infrared camera, which allows access to the phone and it’s popular digital services, like Apple Pay.

These animated emojis come in familiar faces, like the fox, alien, and (not least) big stinking pile of poo. Like old school emojis, these new animojis will be available in the same default messaging app. Animoji’s will only be available on the iPhone X, simply because earlier phones (including the brand new iPhone 8) aren’t built with Apple’s new face-sensing 3D hardware.

The iPhone X's new facial recognition hardware tracks over 50 muscle movements in your brow, cheek, lips, jaw, and mouth. When added together, the movement of these different facial features — such as the formation of dimples — gives the phone the facial data it needs to create a similarly expressive animoji.

What's more, animojis can talk. The phone's hardware doesn't just recognize facial expressions, it matches your voice to animated animojis, so that a fox or unicorn can say your recorded message to whomever you're messaging.

As shown during Apple's iPhone event, a bewildered animated panda in the messenger app asked, "Where are you?". To prove the Animoji feature's worthiness at the September 12 Apple iPhone event, an Apple presenter used a fox animoji to ask Apple CEO Tim Cook a question, to which Cook responded with a laughing alien.

All the different parameters for the Animoji 3D models, presumably Face ID can detect all these states. https://t.co/nQBsfH8i63 pic.twitter.com/TPvZJLWzVA

— Benjamin Mayo (@bzamayo) September 9, 2017

These face-mimicking emojis, while an attractive feature, shouldn't be too great a surprise. Apple has been acquiring facial recognition technology for years, including the companies PrimeSense and Faceshift. And in 2016 Apple bought the hugely relevant company Emotient, which uses sophisticated algorithms to scan subtle changes in faces and determine the associated emotions.

Unlike the security and privacy concerns associated with iPhone X's facial recognition system — which unlock a user's phone — animoji's are just a cool, dynamic feature. Although, it might be a little unsettling to see a digital cartoon of a monkey mimicking how you feel.