Wallemia sebi spores. Wallemia sebi is a xerophilic mold (fungus) that can grow on relatively dry substrates (i.e., at a low water activity). W. sebi is found indoors on dehydated fruits, jams, bakery products, salted beans and fish, bacon, and even fabrics. It is also present in soil and hay. The latter source may be one of the causes of farmer's lung disease. Enhanced SEM. Image width: 35.5 micrometers. Magnification: 2,817x if the image is printed 10 cm wide.