We have this at the foot of one of the trees in our yard. It is hard, waxy feeling, and looks like it has another tree growing out of it.
The tree appears to be healthy - other than some ants climbing up the trunk. Does anyone know what the heck this is? Do I want it? If not, how do I get rid of it? Geeze - we just got the aphids under control and the beans and chives are happily living 6' apart. Now we get this!
It looks to me like some sort of shelf fungus (perhaps Fomes spp. or Ganoderma spp.?). The white part toward the bottom is the spore bearing surface. There is a great dichotomous key in the book Mushrooms Demystified by David Arora that might help you out.
Principal - Terra Phoenix Design
It looks like Fomitopsis pinicola to me. Another possibility is a Gandoderma species. Both of these are medicinal fungi, used in alternative (Chinese) medicine. Ganoderma have brown spores, Fomitopsis have yellow/white. What part of the country is this growing in? What kind of tree is it growing on?
There is no "getting rid of" this type of fungus. It will be living in the tree until the tree dies, and will continue to live in the dead tree, slowly digesting it and turning it back into soil. While the US Forest service might consider these to be parasites, it is highly debatable whether these fungi are actually harmful. There is some evidence that infection with certain types of fungus protect the trees against other types of more harmful infection.