Gillyweed is a plant that looks like seaweed and is very rare. If you eat it you grow gills and fins for about an hour and can breathe and swim underwater. It tastes absolutely disgusting and the texture is crunchy and fresh. It’s mainly native to the Mediterranean Sea. It will only grow and survive in salt water. It’s grey/ green and slimy and looks like rats tails. It’s also used for potion making as an ingredient.