The elongated stems are most likely due to lack of fresh air exchange. The oyster mushrooms in this video were not eaten, as we don’t know the chemicals used to print this old phone book (old inks contain heavy metals). This video demonstrates how oyster mushrooms grow on various substrates. This old phone book is made from recycled paper and sawdust. Oyster mushrooms are saprophytic, meaning they feed on decaying organic matter like wood and other plant debris, made of cellulose, hemicellulose,