Question
I live in the midwest, denison, iowa to be more specific. And i have a tree near my house that is growing a bright yellow fluffy looking fungus or something. when i touch it with a stick it is sort of soft. it's growing on the side of the tree that doesn't get much sun. I'm not sure what kind of tree it is, but was wondering if this is harmful to the tree, or animals, people, or does it mean my tree is sick and should be removed?

Answer
Sounds like the fruiting bidy of on of the decay fungi. The fungus grows inside the trunk of the tree and slowly decays the wood making the tree eventually hollow. It will not kill the tree. The fungi puts out a fruiting body (mushroom like) that contains spores which will fly with the wind to other trees or wood. A tree will live many years being hollow and the only concern could be breakage by high winds. If the foliage is green and healthy looking the tree is ok.