In a way, the sign of the fish was a little like a Q-drop. And, in the early days of Christianity, the sign of the fish was a secret indicator of paths to hidden meeting places for the early (very illegal) Church. Those who were seeking, followed the paths marked by the sign of the fish to gather with other Christians. Yes, it was risky - because haters would also sometimes follow those paths and find gatherings of worshipers of Jesus. The resulting betrayal could lead to the deaths or imprisonment of many. Thank you for asking!