Spirulina is an organism that grows in both fresh and salt water. A relative to blue-green algae, it produces energy out of sunlight and has been used by everyone from the Aztecs to NASA, who proposed that it could be growing space as a nutritional source for astronauts.
A powerful antioxidant, it is particularly effective, in theory, against oral cancers and is good for controlling blood sugar levels. Not a cheap superfood (most of them aren’t) but in pill form, it’s usually just as reliable as loose powder. Mix it in smoothies for a good, vitamin packed energy boost.