Add the softened butter to a medium-sized bowl.
Mix well with an electric mixer, or by hand using a silicone spatula.
Once the butter is smooth and whipped, add the lemon juice and mix again.
Add the crushed dulse (or seaweed of choice) to the butter, and mix again until well distributed.
Taste and adjust salt to your preference.
Place a piece of parchment paper on a flat surface, and bring the butter into one solid mass.
Drop the butter onto the sheet of parchment paper, and use clean hands to pat it into a log shape.
Use the parchment to roll it into a tight log, and twist the ends of the paper to seal them.
Place the butter in the fridge on a flat surface and chill for at least 3 hours before serving.
To serve, unroll and cut into slices. Serve with your favorite seafood dishes or as a topping for a delicious grilled steak, baked potatoes, or the dish of your choice.