Kingdom: Fungi
Division: Ascomycota
Subdivision: Pezizomycotina
Class: Sordariomycetes
Subclass: Xylariomycetidae
Order: Xylariales
Family: Xylariaceae
Genus: Daldinia
Species: D. concentrica
Binomial name Daldinia concentrica
Common names: King Alfreds Cakes, Cramp balls,

These always grow on wood. They look and feel like hard half-round balls.
When cut in half, concentric bands of light and dark colours are seen. See photo below

This fungus is a useful form of tinder for fire-lighting. It does need to be completely dry, whereupon it will easily take a spark. It burns slowly, much like a charcoal briquette, with a particularly pungent smoke. Once lit it is quite difficult to extinguish but fragments can be broken off and transferred to a tinder ball to create an open flame. Maoris used to cart fire from one place to another using this fungus, 
A video on its use in firefighting can be found at the bottom of this page.

Daldina concentrica grown on an old log
Daldina concentrica King Alfreds Cakes .JPG

Daldina concentrica King Alfreds Cakes -001.JPG 

Daldina concentrica-001.JPG

Daldina concentrica.JPG

Daldina concentrica cut  in half showing the concentric bandsDaldina concentrica-10.JPG

The following fungi of the same genus and to date unable to identify.Unknown Fungi 1.JPG 

A video on identifying Daldina concentrica and its use as a firefighter.
VIDEO

Thanks to Wikipedia for text and information http://creativecommons.org/licenses/by-sa/3.0/