Ichthys

The ichthys or ichthus (/ˈɪkθəs/; from Greek ἰχθύς, "fish") is, in its modern rendition, a symbol consisting of two intersecting arcs, the right ends extending beyond the meeting point so as to resemble the profile of a fish. It has been speculated that the symbol was used 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". This symbol is widely used by Christians as a sign of their faith, often being found on vehicles, necklaces and laptop stickers.