The Mysterious Cone Nebula . ... For example, the origin of the mysterious cone-shaped region seen on the far left remains a mystery. ... Other features in the image include red emission from diffuse interstellar hydrogen , wispy filaments of dark dust , and bright star S Monocerotis , visible on the far right. ... The dark Cone Nebula region clearly contains much dust which blocks light from the emission nebula and open cluster NGC 2264 behind it. ... NASA Official: Jay Norris. ...