It is interesting in several different ways, because I was speculating on how it is being done before current cease fire. Everything seemed to be point to Yuan ( or other non-USD currencies ), which then are more easily settled by vessel owners and likely buried under some non-descript names like fees to be , maybe, questioned later its all done.
edit: And it seems I was wrong despite it being my initial thought in terms of used rail.
It's a sad indictment of the RMB that Iran would rather use BTC for bypassing US sanctions.