Snape and the Marauder's Map

'"Professor Severus Snape, master of this school, commands you to yield the information you conceal!" Snape said, hitting the map with his wand. As though an invisible hand was writing upon it, words appeared on the smooth surface of the map. "Mr Moony presents his compliments to Professor Snape, and begs him to keep his abnormally large nose out of other people's business." Snape froze. Harry stared, dumbstruck, at the message. But the map didn't stop there.' (Harry Potter and the Prisoner of Azkaban, p. 211, UK edition). Check out the detail in the background!