Thanks!! I was hoping someone might drop a tip like that, so I kept the notification around. Indeed.. After a long press, it reveals that it's owned by the Evernote[1] app. Apparently it comes preinstalled. The gear button results in a crash, but I was able to block notifications under the info icon. Probably best to take the time and purge all the bundled apps, before another one pops up.

[1] https://d17oy1vhnax1f7.cloudfront.net/items/1Q1L2Y2f3R3v0m1n...