Viemärin vaanija

When Kat's family moves into their new house, she finds an odd sponge under the sink. It's small, round, warm, and pulsing, and it has eyes! Bad things start to happen, and Kat notices the sponge seems more and more excited. At school she and her brother find it listed in an encyclopedia. It's a supernatural creature called a Grool that thrives on others' bad luck. And once you have a Grool, you can't give it away or kill it with violence.