Legends of mermaids exist in every seafaring culture and has even made an impact on scientific conjecture with the Aquatic Ape Theory.
There is probably no other mythical creature upon whom we impute so many of our cultural traits, as the mermaid.
This version is of Thessalonike, the sister of Alexander the Great, who, as legend would have it, turned into a mermaid after her death. She would stop sailors and ask them one question: "Is King Alexander alive?". To guarantee safe passage, there is only one correct answer: "He lives and reigns over the world".