Beefsteak fungus

Beefsteak fungus (Fistulina hepatica) is often found on oak, although I've found it on sweet chestnut in the past. At its early stages is doesn't appear to affect the strength of the wood, and has been known as the cause of 'brown oak' timber but as the disease progresses a brown rot develops due to the fungus preferentially eating the cellulose in the wood and leaving the darker coloured lignin intact.
It is usually associated with the base of trees. The highest I recall seeing it on a tree is around 1.5m above ground level.
The fungus is either red or pinky-brown and is fleshy to the touch. When I touch the fungus the feeling of flabby, fleshy weight in my hand suggests to me a cow's tongue rather than a beefsteak.If you cut it the inside flesh is pale pink with darker pink flecks. The fruitbody usually has a short, thick stem which sticks out of a wound or damaged part of a tree. It can be quite large, sometimes as wide as 40cm or so.
My most authoritative fungus book (Encyclopedia of Fungi in Britain & Europe, M Jordan) says beefsteak fungus is edible and tastes slightly acidic. I've never been tempted to try it.