"C" PLUS
'(<a href="http://www.j-archive.com/media/2006-12-07_DJ_07.jpg" target="_blank">Jon of the Clue Crew presents the clue with a video monitor.</a>) The two-dimensional Necker cube can be translated to three dimensions by your brain - it was named for Necker, who was noted for his study of these, a term for many solid symmetrical objects'
crystals