Fused display up top, fused sensor array below—we won't find anything but broken pieces if we bust this apart, so let's switch on those X-rays from Creative Electron again for a better look.

The dark rectangle in the center is a dense magnet for centering the charger (and may also help wick away heat from the S6 package). It's surrounded by the control board for the down-firing LEDs and sensors, and the ropey coils of copper for the inductive charger.

And here's the (reassembled) pulse oximeter communicating with aliens lighting up in Christmas-y fashion!

By shining red, green, and infrared light into your skin, then sensing via photodiode how it bounces back, the watch can tell how oxygenated your blood is (redder means more oxygen).

Low blood oxygen levels (hypoxemia) can be an indication of COVID-19 or other serious medical issues.

The Apple Watch doesn't track body temp like the Oura Ring 2 does. But while both measurements are informative, neither is meant to provide hospital-grade certainty.

As a reminder, we're not health experts—so read up! Find out more about how blood oxygen tracking works at CNET, or a lot more at the Respiratory Medicine journal.