This fungus grows directly on the corn kernels and if it grows large enough it can be seen through the husk. It is blue-grayish with some white and looks similar to most mushrooms with a soft and velvety texture. It has a very pungent earthy, sweet yet savory and woody taste with flavors of mushroom and corn. It is harvested two or three weeks after the corn has become infected.
Corn smut, Mexican truffle, huitlacoche is a plant disease that grows on ears of corn around the kernels in puffy, gray clouds that look kind of like river stones. But when you take this strange fungus into the culinary world, huitlacoche becomes a delicacy used in all sorts of dishes from soups to enchiladas to sauces.
 
This culture has been sucessfully used by Alaric Strauss (1st two pics.) as well as a few others to grow huitlacoche (Corn Smut) by injecting where the ear meet the stalk right after silk started forming.