Fibroporia vaillantii

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Fibroporia vaillantii, also known as mine fungus, white pore fungus, Antrodia vaillantii, Polyporus vaillantii, and various other names is a wood-decaying fungus which can occur on timber in humid conditions. The fungus causes brown rot of pine wood, in which cellulose and hemicellulose are broken down, leading to brown discoloration and shrinkage of wood.

Summary from Wikipedia