Foundlings
Anonymous foundlings were a naming problem for civil registrars, but such anonymous children were often named toponymically, after the town where they were found. Because most foundlings were reared in church orphanages, they were often given the surnames Iglesia or Iglesias (church) and Cruz (cross). Blanco (connoting "blank" here, rather than the more usual "white") was another option. A toponymical first surname might be followed as second surname by Iglesia or Cruz.
Foundlings often were surnamed Expósito (Lat. exposĭtus, "exposed", connoting "foundling"), which marked them, and their descendants, as of low caste and social class, people without social pedigree. In the Catalan language the surname Deulofeu ("made by God") was often given to foundlings. In 1921 Spanish law allowed the surname Expósito to be changed without charge.
In Aragón, anonymous children used to receive as well the family surname Gracia (Grace) or de Gracia, because they were thought to survive by the Grace of God.
Read more about this topic: Catalan Name, Denotations