The account @StellaFudge today shared photos of an alleged Apple Watch Series 10 prototype with a unique health sensor design. The health sensor on the prototype has a smaller array of LEDs compared to actual Apple Watch Series 10 models that launched last year. There is also an extra ring of l ights around the sensor's perimeter, but it is unclear what it is for. The prototype was running an internal build of watchOS 11.1 that was never released to the public, according to @StellaFudge. Prototype Apple Watch Series 10 with… A very unique health sensor arrangement.The health sensors got shrunk down a lot and there was an extra light ring around the perimeter. The watch is also running an unreleased build of watchOS11, somewhere between 11.1b5 and 11.1rc. pic.twitter.com/8n06JkQT39— Stella - Fudge (@StellaFudge) March 31, 2025 The health sensor on the back of the Apple Watch is used to measure the wearer's heart rate, as well as blood oxygen on models sold outside of the United States only due to a patent dispute. It is unclear why the sensor looks different on this prototype, but the changes likely related to Apple testing future health features for the Apple Watch. For example, Apple has reportedly been testing a feature that could alert you to signs of high blood pressure. This feature was first rumored a few years before the Apple Watch Series 10 launched, but Apple continues to face development challenges. It is unclear if the feature will be ready in time for the Apple Watch Series 11.Related Roundup: Apple Watch 10Buyer's Guide: Apple Watch (Neutral)This article, "Apple Watch Series 10 Prototype With Unique Health Sensor Revealed" first appeared on MacRumors.comDiscuss this article in our forums ...read more read less