ORKNEY, SCOTLAND—Incised “butterfly motifs” appeared in a wall at the Neolithic site of the Ness of Brogdar as sunlight hit the stone blocks at a certain angle, according to a report in BBC News. The markings are so faint they have not yet been caught in a photograph. Antonia Thomas of the University of the Highlands and Islands said the images may have appeared to move as the sunlight traveled over them during the day. The site, located near the standing stones known as the Ring of Brodgar, consists of Neolithic ritual and domestic buildings. Other stones will be examined to see if incised marks were overlooked. To read in-depth about the site, go to "Neolithic Europe's Remote Heart."