Spirulina is a cyanobacterium is made primarily from two species of cyanobacteria, however it is the Arthrospira platensis, that is cultivated worldwide for consumption by humans as a dietary supplement. It can also be taken in the form of whole food's, tablets, flakes and powder.
In the days of the Aztecs, spirulina was used by many tribes and other Mesoamericans until the 16th century. The Aztecs called it 'techuitlatl'. In the late 1960's it was discovered by French researchers in abundance at Lake Texcoco, but there is no reference to its use by the Aztecs as a daily food source.
Around the small lakes and ponds of Lake Chad, spirulina has been traditionally harvested, dried and used in cakes called dihé. These are then used to make broths for meals, and also sold in markets. When spirulina is dried, it contains about 60% protein and includes all essential amino acids, though with reduced amounts of methionine, cysteine and lysine when compared to the proteins of milk, eggs and meat.