Spirulina is an edible blue-green algae and is believed to be one of the oldest lifeforms on earth. Spirulina has become a popular alternative to multivitamins as it is a highly nutritious natural supplement with high levels of vitamins, minerals, protein, carotenoids, and antioxidants. Blue Spirulina is a type of spirulina with a higher phycocyanin content than normal giving it a deep blue color.