Nightly Butterfly animation with particles effect.
Tested on Oculus Go (with touchpad) and VR BOX2 (with joystick). For tests on a desktop (Windows 10 + Chrome) the "inline" webxr session and A,S,D,W,↑,↓ keys for navigation are used.
See also beautiful Effects Animation Butterfly.
WebXR samples     updated 12 Apr 2020