If you scroll all through your Settings >> Apps menu, do any of the apps in the listing appear to be at least similar in some way to that icon? Be sure that any show System apps option is enabled so you'll be viewing all the installed apps (apps you installed along with all the pre-installed apps.) The thing is, that Status bar at the top of our phones can contain a confusing mix of app notification icons plus various Android services icons.
If might show the icon with name if you swipe down twice on the Status bar, that's been a common way to expand the icon menu.