Peniophora is a corticioid genus, which means the fruit body is two dimensional and visually is much like a coat of paint or a thin skin and appears on wood.
There are several species of grey to greyish-violet Peniophora and identification to species is a microscope job. The surface is more-or-less smooth and featureless, but polygonal cracking is sometimes abundant.
In Australia the Peniophora 'grey/violet' group can be found in a wide variety of habitats from wet forests to semi-deserts. The fruit bodies are commonly found on the underside of dead wood that is lying on the ground, but you may find them also on the undersides of dead branches still attached to live trees. The greyish colours can make them cryptic (especially on the smooth, grey, well-weathered, dead branches that are common on eucalypts).
Sometimes a grey/violet Peniophora may, at first glance, be mistaken for a species of Hymenochaete with a grey-brown fruit body. However, a 10 times hand lens quickly puts you right since Peniophora fruit bodies lack the tiny bristles (or setae) that are present in Hymenochaete (see http://canberra.naturemapr.org/Community/Species/15577).