The ichthys or ichthus, from the Greek ikhthū́s is a symbol consisting of two intersecting arcs, the ends of the right side extending beyond the meeting point so as to resemble the profile of a fish. It has been speculated that the symbol was adopted by early Christians as a secret symbol; a shibboleth to determine if another was indeed Christian. It is now known colloquially as the "Jesus fish".
An early circular ichthys symbol, created by combining the Greek letters ΙΧΘΥΣ, Ephesus.
Funerary stele with the inscription ΙΧΘΥϹ ΖΩΝΤΩΝ ("fish of the living"), early 3rd century, National Roman Museum
An ΙΧΘΥΣ ("ichthys") fish symbol on a car
The Catacombs of Rome are ancient catacombs, underground burial places in and around Rome, of which there are at least forty, some rediscovered only in recent decades.
A Eucharistic fresco, Catacomb of Callixtus
Good Shepherd fresco from the Catacombs of San Callisto.
Carved Roman Sarcophagus
An earlier catacomb wall art, depicting Adam and Eve from the Old Testament.