Tiny text box stuck on desktop

Strangest thing! While typing away I must have hit some strange combo of keystrokes to produce a very small text box which seems to be stuck on my iMac desktop screen, running OS X Catalina. It is not moveable, it is not an icon, it's not a real text box shrunken in size. No app is running, it cannot be selected or made larger except by adding text and delete only removes the text, never the box. It's almost like a hole in the desktop to a tiny texting app hiding behind it. (I know, sounds crazy!) I'll attach a screenshot.