Apple has updated the infamous Spinning Beach Ball of Death (a.k.a. the Spinning Pinwheel, Pinwheel of Death, etc) in OS X 10.11 El Capitan with a new flatter design.
With the release of OS X 10.10 Yosemite, Apple has transitioned toward a more flat and modern UI design, yet many elements retained their look from previous OS X releases. OS X 10.11 El Capitan appears to be continuing the visual refinement started in Yosemite, also including the Apple Watch font, San Francisco, as the new system font.
Here’s the new Beach Ball in action: