According to an article from this past Sunday by Gail Cameron of The Scottish Sun, the crew recently working on an episode for Series Ten of Doctor Who urgently placed two orders for seaweed totalling £80 over the course of two days to Just Seaweed in Rothesay, Isle of Bute.
The seaweed could, of course, have been for anything. Perhaps the Doctor makes a habit of snacking on sushi after trying it in the upcoming Christmas Special. Or the seaweed - which is edible, by the way - could have been used on costumes or sets. Perhaps the Sea Devils are making a return?