Like most brains, the grey matter in this Series 6 is pretty inscrutable: it's encased in hardened resin, as per usual, making further exploration extremely difficult.

There are a few more conventional ICs piggybacked onto the package, and we can at least spot a Skyworks chip marked 239-7. The other chips are more mysterious, and none is an exact match for the U1 chip we found in last year's iPhones.

Sans-brains, we can see the Series 6 frame has a slightly modified footprint with a narrower lip for the adhesive gasket, which is now carefully routed around the band mechanism.

Apple somehow packed more battery and more Taptic Engine into a (barely) smaller design. Impressive!