Marine snow is made of just about anything—except water.

OCEANS
The term is mainly used figuratively today, but in the past it depended on whom you asked as different cultures gave different answers.
No, a fugitive in a ship is still subject to the laws and regulations of whatever country the vessel is registered to.
When it comes to being mammal, dolphins fit the bill in all respects. They give birth to live young and nurse them. They're warm-blooded. They have lungs and breathe air.