Seaweed is simply the umbrella the term for various marine plants and algae, and many varieties are not only delicious, but also extremely nutritious. They can form the base of salads and broths, and some are sold toasted as standalone snacks. It’s also possibly the most environmentally friendly edible plant there is. Seaweed pulls nitrogen and phosphorus from seawater, helping maintain those nutrients at non-dangerous levels. More important, seaweed is a remarkably efficient carbon sink: Like other plants, it absorbs carbon dioxide from the atmosphere via photosynthesis, but its speedy growth rate means it can do so up to 50 times faster than land-based forests.