I would add that those who are sensitive enough / allergic enough to need to avoid contact or cross contamination, that seaweed is almost inevitably processed in a way that shellfish protein may not be fully removed. The risk is less for large pieces of seaweed used for cooking stock that you can wash well, and higher for more processed items like sheets of seaweed for wrapping rice, or snack seaweed, or crackers with wrapped dry seaweed, or things like furikake with seaweed, meant to be...