I got a Korean melon this weekend from a Korean grocery store, it was very good, so I wanted to save the seeds. After googling, I rinsed off all the other stuff from the seeds and then put the seeds in a bowl of water, ALL of the seeds floated to the top, none sunk to the bottom. Does that mean that none of the seeds are viable? Is it because the melon was probably not riped yet when they picked it?