As a matter of fact, Seedless watermelon production began its evolution in 1939. Though this watermelon lacks the large hard black seeds of its traditional counterparts, it can still contain small white seeds that are soft and completely edible. Besides, Seedless watermelons can be oblong or spherical in shape, and have a densely compacted magenta flesh that is crisp yet succulent. Not only are watermelons 92 percent water, they’re also full of magnesium and potassium. We often lose these two minerals, along with sodium, in our sweat during exercise, and they need to be replenished immediately. Potassium and magnesium help carry the electrical signals in the body and allow our muscles to contract and relax.