I was changing my wallpaper and I saw one with a clock on the lower right. I choice it and it was not there. So it is indicating it does something.
This is most likely me being blind.
11 Answer
Let me give you a hint:
Changes throughout the day
This wallpaper will automatically cycle through all of the default wallpapers shipped with Ubuntu once every day.
Its behaviour is configured in a file /usr/share/backgrounds/contest/*.xml, with the file name normally being equal to your Ubuntu release name (e.g. xenial.xml).
