This is a picture looking up my chimney cleanout. It sort of looks like it was filled with debris, but also sort of looks like it was intentionally blocked off. It is used to vent the gas furnace and hot water heater. Anyone have an idea if this is blockage that needs to be removed or does it serve a purpose?
I recently had a chimney sweep out to inspect and clean my fireplace on a new-to-me 45-year-old home. He told me that all those cleanouts are good for is giving rodents a nice entry into the house. He recommended that I fill it up with ash and never open it again. I suspect that the previous owner of your home was working under the same idea.