ICHTUS or ICHTHYS
Ancient Christian symbol. The word “Ichthys” means fish in Greek, but also stands for -"Iesous Christos Theou Yios Soter", meaning "Jesus Christ, Son of God, Redeemer." It is believed that it originated at the time when Christianity was persecuted. When a Christian believed that someone else was also a Christian, they drew an arc on the ground. If the other person actually was a Christian, they drew another arc which formed this symbol where it crossed with the first.