In Spidersilk Mark actually fights off ghosts who appear in a black mist during one of his “dreams.” The ghost are defeated using different items that Mark finds throughout the book, which create a sonic blast that gives the ghosts a bit more than they bargained for. The ghost, as resilient as they are, begin to reform but there is one major change in them..their noses are white. This is due to the fact that the ghosts were actually blown away by the blast and when they came together they actually breathed in a bit of Mark's atmosphere, which is something they didn't want to do. The white represents a change in them and is used as a direct contrast to the black so it is easy to the change. The ghost scatter knowing that they are now changed.