What is the proper inquiry in the ambergris and khums discussion?

Argument Without New Proof: Absence of a Cause and Presumption of Continuity

• Physical similarity of ambergris and fish suffices as cause for khums
• Which legal category attracts khums, and whether ambergris belongs to it
• Different names of marine products necessarily produce different rulings
• Ambergris is valuable, so the levy depends only on its commercial gain