Cairo, Egypt - First came the fish bumper stickers, imported from the United States and pasted on cars by members of Egypt's Coptic minority as a symbol of their Christianity.
Before long, some Muslims responded with their own bumper stickers: fish-hungry sharks.
It's not exactly war at sea, but the competing symbols that have cropped up on Cairo streets are a tiny reminder of the tensions between Egypt's Copts and majority Muslims.
Some Christians are annoyed at the Muslim response.
"All I wanted to say is that I am a Christian, kind of expressing my Coptic identity," said 25-year-old Miriam Greiss, who has a fish sticker on her car. "I think choosing a shark doesn't make sense, as if someone is saying, 'I am a violent, bloody creature, look at me."'
Emad, a Muslim, laughed when asked about the competing symbols but was unapologetic about the two shark stickers on his car.
"The Christians had the fish so we responded with the shark. If they want to portray themselves as weak fishes, OK. We are the strongest," said Emad, who would give only his first name.
Sociologist and human rights activist Saad Eddin Ibrahim is a Muslim who has studied discrimination against Copts. He called the sticker symbols "superstitions" but said that in Egypt's climate of religious fundamentalism, people with bad intentions could use them to ignite tensions between Muslims and Christians.
"There are people who want to make use of the decay we live in," he said.
Relations are generally calm between Copts, an estimated 10 percent of Egypt's more than 70 million people, and the Muslims who make up virtually all the rest. Tensions occasionally erupt into violence, and Copts complain of job discrimination and being shut out of a share of political power.
The complaints, though, are spoken softly. Copts - who trace their history to St Mark's bringing Christianity to Egypt soon after the death of Christ - didn't survive Roman persecution and Arab conquest by being overly assertive.
Copts often wear gold cross pendants or have tiny crosses tattooed on the inside of their wrists, but the stickers seem a more public step. Karl Innemee, a specialist in Coptic studies at the American University in Cairo, said the arrival of the fish could reflect a new desire by Egyptian Christians "to express themselves openly."
Still, the Coptic businessman who began importing the fish stickers two years ago refused to give his name when contacted by The Associated Press at the Maria Group - the company name on the stickers. He said discussing religion could be asking for trouble.
The fish stickers are sold in churches or Christian bookstores for 50 piastres (about 8 US cents). The Maria Group owner said sales of the fish, which come plain or with the word "Jesus" inside, have picked up in recent months - soon after the shark stickers first appeared in August.
No one seems to know where the shark idea came from.The stickers are sold in Islamic bookshops and also come plain or fancy - some with the Arabic phrase "No god but Allah" printed in the shark's body.
While the fish stickers came from America, the symbol has roots in Egypt. In their earliest days, Copts used the fish - the emblem may be from the Bible - as a way to identify themselves to each other without letting their Roman rulers know.
Medhat Mahrous, a Coptic scholar, noted that the Coptic church still uses the fish symbol today on altar curtains and religious objects.
The fish v sharks on Cairo streets are reminiscent of how proponents of the theory of evolution responded to similar-looking fish stickers in the United States.
After the Christian-derived fish stickers began appearing on US cars, similar depictions of the started popping up - some with tiny legs, sometimes with the word "evolve," others with the name "Darwin" printed inside the fish.
Back in Cairo, the latest Muslim sticker depicts a shark chasing a fish. - Sapa-AP