He might be the same person as Lucius Flavius Hermadion
who offered a Mithras rock-birth sculpture
, currently located in Ireland.
Other brothers from Ostia
The altar includes a slab with an inscription for the salvation of two emperors.
Pr(o) sal(ute) Augg(ustorum duorum) / S(oli) i(nvicto) M(ithrae) / [L. ?] Florius Hermadio(n) / sacerdos s(ua) p(ecunia) f(ecit).
For the salvation of the two Augusts, to Sol invincible Mithras, [Lucius (?)] Florius Hermadion, priest, made at his own expense.