about 6% of a watermelon is sugar, which makes it very sweet. there are many different types of watermelon. some have a green rind on the outside and a red-pink flesh on the inside, with brown seeds. some can have yellow flesh, and some can be seedless. the green rind on the outside is not usually eaten, though it can be used as a vegetable. it can also be stewed or pickled. most watermelons are oblong or spherical. in japan, watermelons are grown in different shapes, such as hearts and squares.