If you’ve spent any time dining in Mexico City recently, you may have noticed spirulina cropping up on menus in everything from the usual smoothies to more traditional dishes such as tortillas and tlayudas (a crisp tortilla base with refried beans and other toppings). Centuries before spirulina was deemed a “superfood”, the vibrantly colored cyanobacteria (or blue-green algae) was a pre-Hispanic dietary staple.