Have you ever seen strange things you couldn't; explain?

30 years ago, I was walking through a graveyard!! i came across a grave , this tombstone had a picture of this man on his tomb stone. it looked so life like , it was very scary. I remember this guy he was a friend of my mother .One day he ask a friend to took his picture .he was standing in front of his home, and after the picture dried they pull the paper off,.the Strangers thing HIS great mother was standing above him. his grandmother died 8 years ago how did she get in the picture/? This happen in the 70's