Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Polyporales
Family: Fomitopsidaceae
Genus: Fomes
Species: F. hemitephrus
Binomial name: Fomes hemitephrus

Fomes hemitephrus is in the order of Polypores which are a group of tough, leathery poroid mushrooms similar to boletes, but typically lacking a distinct stalk. The technical distinction between the two types of mushrooms is that polypores do not have the spore-bearing tissue continuous along the entire underside of the mushroom. Many polypores are bracket fungi.
This species is found in Australia and New Zealand, and is one of the most common polypores in those countries, causing a white rot on several tree species. Fomes hemitephrus is often found on rotting logs but has been found growing on the trunks of a living kamahi tree. They are rot-resistant to the extent that they themselves often last long enough for moss to grow on them. Rot-resistance is due to the mushroom's ability to produce compounds with anti-pathogenic activity.

Fomes hemitephrus bracket fungi..JPG

Looking at the underside
Fomes hemitephrus bracket fungi.-1.JPG

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