I have discovered what happened to my 'Photos' app.
A while back, I was attempting to improve my battery life and reduce data usage by disabling apps that were running in the background.
I ended up disabling Google+ because I wasn't using it anyway (or so I thought).
After doing an app search for "Google photos" in Google Play, the Google+ app showed up in results and was labeled as disabled.
On a whim, I enabled Google+ in my app manager.
Both Google+ and Photos now appear, side by side, in my apps list.
Opening the Photos app, a photo editing icon labeled "Drama" is located on the bottom of the screen.
I now realize that Photos is the app that I had been missing, and is, apparently, inseparable from Google+
I hope this helps someone else who might have the same problem.
belodion, thanks for your help.
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