Why are random photographs appearing in 'my files' tab?

[AC Question]

I bought my tab 4 on Monday, on 2 occasions I opened the my files app and found photographs A) I have not taken or looked at via fb etc on this device and B) photos of people I have no idea who they are.... I deleted and some have reappeared. Can anyone help with why this is happening and how to prevent it in the future? Thanks

 

[B. Diddy]

Welcome to Android Central! They're probably cached thumbnails that the browser or other apps temporarily save to storage for easy access later.