According to one account, Maurus was of noble Roman birth, and became the city's first bishop.

[2] The earliest basilica in Poreč, dating back to the second half of the 4th century, held the relics of Saint Maurus and was dedicated to him.

[3] In the present basilica, constructed in 553, Maurus is depicted in one of the mosaics on the apse.

He is also portrayed in an apse mosaic in the Chapel of San Venanzio at the Lateran Baptistry.

The chapel was commissioned by Pope John IV, a native of Dalmatia, to commemorate the saints of his homeland and Istria.