O is the letter for today’s Saint. This gives us our saint, Saint Opportuna of Montreuil:
Saint Opportuna of Montreuil (died 770) was a French Benedictine nun and abbess. A Vita et miracula Sanctae Opportunae was written within a century of her death (ca 885-88) by St. Adalhelm (later rendered Adelin), bishop of Séez, who believed he owed his life and his see to Opportuna.
More can be learned about her at her wiki, found here.