I suppose you could call me...Soot," said the thing. "Yes...Soot. I have breathed it, lived in it, and eaten it for so long that it is a fitting name." "Eaten it?" asked Suzy. "Why eat soot?" "Boredom," said Soot.
Garth Nix (2010). “The Keys to the Kingdom #2: Grim Tuesday”, p.170, Scholastic Inc.