The "Hidden Mother" is a type of 19th century photo where a child is photographed sitting in his or her mother's lap. Later, the photo is matted or framed to hide the mother, leaving just the calm child in view. To make the cropping less obvious, the mother was sometimes wrapped up in fabric. Remove the frame or matte though and you're left with a delightfully creepy photo.
David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.