Fibroporia vaillantii, also known as mine fungus, white pore fungus, Antrodia vaillantii, Polyporus vaillantii, and various other names[1][2] 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.

[3] In humid atmospheres, the white cotton-like mycelium can grow on wood surfaces and cross inert materials.

In newly grown mycelium, fine drops of clear liquid may be present.

[2][3] The fruit body is an irregular white plate with a thickness of 2 to 12 mm.