The best-known of the Edo groups, the Okpella, use a wide, varying range of mask types, which, according to some African artists, may take up to a year to complete. The masks that are created by the artist convey many different types of rituals and ceremonies. One example of this is a brilliant, white-faced mask representing “dead mothers”, appearing during the annual Olimi festival, which is held at the end of the dry season, and is worn by dancing kinsmen. This festival, as others do, signifies social control and ancestral reverence, celebrating the transitions of age-grades.