Hi Pam, Hard to tell from this distance: With a magnifying glass or handlens, do you see on the surface - pores? any surface texture? if it has a mushroom or shelf shape (the bits on the ground) what does the underside surface look like?
How hard it is? Like a wood? Like a carrot? Like a potato? Like an apple? Like a plum? Like a raspberry? Or even softer? From the look it resembles a young fruiting body of a Serpula lacrymans or maybe of a Heterobasidion annosum. But these are pretty soft when they are so young and still white whole. Indoors is suitable habitat for S. lacrymans, not for H. annosum.
I believe some of the issue is white mold, it's powdery. The other is a type of fungus that's almost like rubber, other is crumbly and porous. I have someone coming tomorrow to tear the wall out and treat if needed.
