Remove Circle Icon in Notifications A new icon appeared in my notifications today. It looks like Remove Circle from the Material icons, except with an additional outline.

There's no info/action when I try to press on it; if I try to drag the notification section down, the icon disappears until the section collapses back.

Rebooting did not remove it.

It looks almost like the left-most icon on the right side of this screenshot (source):
That icon certainly looks like a do not disturb icon (DND). 

You can turn it off from quick settings or in Settings >> Sounds  >> DND