A worm whose favorite dish is – of all things—worm larvae has to take great care not to accidentally devour its own progeny. How these tiny worms of merely a millimeter in length manage to distinguish their own offspring from that of other worms and avoid cannibalism has recently been discovered by scientists at the Max Planck Institute for Developmental Biology in Tübingen. They found that Pristionchus recognizes its offspring by means of a complex mechanism. The worms carry a small, highly variable protein on their surfaces, which seems to be detected by the worm nose. The variable part of the protein likely functions as a self-recognition code and the change of even one amino acid leads to cannibalism.