An inscription mentions that he was Pater et sacerdos of the invincible Mithras. He was married to Cosia Primitiva, whom he calls a worthy wife, and was of the house of Augustus. He was active in the city of Rome about the beginning of the second century.
Other brothers from Roma
This marble plaque was made by a Pater and priest Lucius Septimius Archelaus of Mithras for him, his wife and his freedmen and freedwomen.
D(is) M(anibus) / L. Septimius Aug(ustorum trium) lib(ertus) Archelaus / pater et sacerdos invicti / Mithrae domus Augustanae / fecit sibi et Cosiae Primitivae / coniugi benemerenti libertis liberta/busque posterisq(ue) eorum.
To the gods Manes. Lucius Septimius Archelaus, freedman of the three Augustans, Father and priest of the invincible Mithras, of the house of Augustus, made (this plaque) for him and Cosia Primitiva, his deserving wife, for their freedmen and freedwomen and for their posterity