I know of a few apps that do this for example an app called hide it pro. I hides behind an app called audio manager and in order to get to it you have to do a long press on the title and enter a pass word to open the app. the app doesnt show in your app tray or anything and the audio manager actually can control your volume and everything.
well I was about to take a pic with my girls phone and noticed a random app called magnifier. when you open it it just goes to a crappy camera app with no special features. the app doesnt show in the app drawer nor does it show in google play ass downloaded. I even checked in the app manager and still nothing. anybody know anything about this or heard about this? i even googled it and there is no such app with that same icon picture.