CIMRM 554-555 - "Chrestus the pater and Gaurus" tauroctony. Vatican, Rome.
A tauroctony bas-relief with a Greek inscription. It may be found in the Vatican museum, in the room of the animals, and is behind the large free-standing tauroctony of CIMRM 548. Note that casual visitors are not allowed into the room (in 2014), but must remain behind the rope in the corridor, which is why all the photos are from one side.
I.e. "Chrestus the Pater, and Gaurus, dedicated this."