While I agree in part, that is not a definitive test. If it floats, that means a substantial volume of air pockets or other voids formed during melt/freeze cycle. While this occurs frequently, it does not occur nearly all the time.
Waiting on P Nut to share his evidence.
Time for more coffee.
I had to say that. And I will say this to P-NuT, welcome to the forums and learn to grow a thick skin because folks here will try to get under it. We are a big family and sometimes some of us get a little testy. It is not meant as a personal assault on you. Please continue to share your finds with us, maybe even identify something for us. Good luck on your future hunts.