How does wood affected by white rot appear in its later stages?

In the later stages of white rot, wood undergoes significant degradation, where the structural integrity of the wood is compromised. The fungus responsible for white rot breaks down the lignin and some of the cellulose within the wood fibers, leading to a distinct texture change. As this process continues, the wood becomes soft and spongy, making it easily penetrable and altering its original density. This sponginess can be an essential indicator of white rot's advanced stage, highlighting the severity of the decay and the potential for structural damage.

In contrast, the other descriptions do not accurately reflect the characteristics of wood affected by white rot. Hard and brittle wood suggests a different type of decay or age, while a shiny surface may imply a different treatment or finish rather than rot. Wood that appears completely unaffected would indicate no rot at all, which is contrary to the premise of the question regarding the later stages of white rot.