iPhone 7 -- mail icon has disappeared from home screen

I wasn't doing any clean up of the home screen, didn't delete icons. Grabbed my phone and the mail icon in the dock was gone. Yes, I can search for the app, and my email is still there. It's updating and functional. But the visible icon is gone from the home screen. What's more strange is that if I hit the blank space, I get to the app. I just can't see the icon, nor can I know if there is new mail I should be attending to.

Help appreciated.