I don't think its a horses hoof, it doesn't look tall enough,
But it might be an Artists Conk fungus. Both types usually have some trama/amadou making them usefull. If you can get a piece off without denuding the area, try drying a piece and experiment. I found one once and while the amadou didn't yeild a huge amount, the dried spore tubes make great ember extenders.
Ogri the trog