This aroma can be easily recognized during a blind smell test by anyone who is used to eating or picking mushrooms. It is a tertiary aroma due to aging in barrels, and sometimes it disappears a few minutes after uncorking the bottle, leaving behind an earthy note. It must always be pleasant and never recall mold.
This is not a common aroma of Red Wines and it can be found only in some wines after many years of aging. Some examples are wines made from the Pinot Noir variety, from Nebbiolo and Montepulciano d’Abruzzo.