In Australia, autonomous killer robots are set to invade the Great Barrier Reef. Their target is the crown-of-thorns starfish—a malevolent pincushion with a voracious appetite for corals. To protect ailing reefs, divers often cull the starfish by injecting them with bile or vinegar. But a team of Australian scientists has developed intelligent underwater robots called COTSBots that can do the same thing. The yellow bots have learned to identify the starfish among the coral, and can execute them by lethal injection.