Answer:
I am lighter than the material I am made of. You see parts of me but more of me is hidden underneath.
What is made of water but if you put it in water it will die?
Some people avoid me some people count me some people just consume me
You use a knife to slice my head and weep beside me when I am dead.
I'm blue at day and black at night. I do contain some creatures born and died. What am I?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.