flotsam and jetsam

 Jetsam is that part of a shipwreck that has been thrown overboard (think of jettison) and flotsam that which has floated off of its own accord. (A third type, wreckage found on the sea floor, is called lagan.) There was a time when the distinction was important: flotsam went to the crown and jetsam to the lord of the manor on whose land it washed up.