What happens when seed sinks instantly?

[Mazeblue1]

So I put some seeds in water to start a new grow and one seed sank instantly.
I haven’t experienced this before but have read and heard numerous times that means the seed is not viable.
I thought about dropping another but decided against it and glad I did because it did come up yesterday.
So, morale of story is don’t believe everything you hear, try things for yourself.
Happy growing!