The coarb, however, often had charge of a church which had held comparatively high rank in pre‐Norman Ireland, or one still possessed of relatively extensive termon lands.
[3] Also as per this article "... such lucrative monastic offices as “coarb” (comarbae “heir” to a saint) or “erenach” (airchinnech “superior”), otherwise transmitted by natural or nepotic descent within ecclesiastical families, which were often the politically displaced branches of royal dynasties" The current chief of Clan Livingstone in Scotland was recognised by Lord Lyon as the "Coarb of Saint Moluag" and the "Hereditable Keeper of the Great Staff of Saint Moluag".
When the monks fled to their monastery in Kells, following the 9th-century Viking raids on Iona, their abbot continued to hold the title of coarb to reflect his direct inheritance: many of the early abbots were members of Columba's family.
The abbot of the collegiate church (i.e., monastery following the Rule of St Columba), who held holy orders and celebrated Mass ('serveth the cure'), was responsible for his monastic community.
In time, the pattern of a Bishop and an Abbot of Iona was established, which after the Reformation and the Dissolution of the Monasteries fell into disuse.