TEHRAN, Young Journalists Club (YJC) - The world’s smallest watermelons are now being grown in the city of Chungking. The mini watermelons measure around the same size of a coin. Expert tasters say that the new snack is sourer and tastes like tomatoes compared to regular watermelon. The so-called 'thumb watermelon' is originally from South America. It goes by the name of 'cucamelon', with its insides resembling a cucumber.