"The female honeyguide [bird...] finds a nest made by another bird and lays a single egg in it when the other mother is not around.  When the honeyguide egg hatches, it is blind and hungry and almost helpless, but it has two sharp hooks on its bill.  It uses them to bite the other nestlings to death.  [...]  The mother bird [...then raises this] baby [...], while her own young have been killed."—Thank you, Alvin Silverstein, Virginia Silverstein, & Laura Silverstein Nunn, for Symbiosis, Twenty-First Century Books, 1998, p.7