About Daldinia concentrica (Bolton) Ces. & De Not.
Daldinia concentrica is an inedible fungus known by several common names, including King Alfred's cake, cramp balls, and coal fungus. It is a common, widespread saprotrophic sac fungus that grows on dead and decaying wood. The fruiting body of this fungus is hemispherical, hard, friable, and shiny black, measuring 2 to 7 centimeters wide. It looks like a lump of coal, which gives it several of its common names such as coal fungus and carbon balls. According to legend, King Alfred once hid in a countryside homestead during a war, and was assigned to take baked goods out of the oven when they finished cooking. He fell asleep, and the cakes burned. Daldinia concentrica is said to resemble a burnt cake left from this incident. The internal flesh of the fruiting body is purple, brown, or silvery-black, and organized into concentric layers. Most sources agree that, similar to tree rings, these layers are linked to seasonal growth. The asci are cylindrical and form inside flask-shaped perithecia. When each ascus fills with fluid, it extends outside the perithecium and releases spores. D. concentrica contains several unique compounds, including a purple polycyclic pigment and a metabolite called concentricol, which is oxidized squalene. Many types of insects and other small animals live inside this fungus species. This fungus works well as tinder for starting fires. Brown specimens are usually too heavy and dense to be effective, while black specimens are lighter and work better. It must be completely dry to catch a spark from traditional flint and steel. It burns slowly, similar to a charcoal briquette, and produces particularly pungent smoke. Once lit, it usually needs a constant flow of oxygen to keep burning, such as from swinging the fungus or blowing on it. Fragments can be broken off to expose more embers and transferred to a tinder bundle to start an open flame.
