In the world of fungi there are many similar species, so it is best to start with the common names for groups of similar types.   We call polypores shelf fungus or bracket fungus.

They often grow on trees or stumps in horizontal bodies called conks.   The semi-circular bodies can be quite hard and live for a long time.   They are either parasitic or feed on decaying matter.

There are thousands of types of polypores, a few of which are distinct enough to learn the individual names, but most of us will just enjoy seeing them in the forest and calling them shelf fungi.