The image -- a black hand, with four fingers raised and the thumb drawn across the palm -- is being called "R4bia." It's a reference to the Rabaa Al-Adawiya Mosque, the Cairo site of a pro-Brotherhood sit-in that was violently broken up by Egyptian security forces last week, resulting in the deaths of scores of Morsi supporters.
In Arabic, "rabaa" means four, or fourth. Activists have encouraged social-media users to update their Twitter and Facebook photos with the symbol and the Turkish-based R4bia.com website calls it "the birth of a new movement for freedom and justice."
Variations of the meme have spread online.
This one appears to suggest the four-fingered salute is superior to the two-fingered "V" for victory, which was common among the hundreds of thousands of anti-Morsi protesters who gathered in Cairo's Tahrir Square in late June.
Still in its infancy last weekend, the symbol got a boost from Turkish Prime Minister Recep Tayyip Erdogan on August 17, who raised four fingers in a show of solidarity at a rally in the northwestern city of Bursa.
The Turkish leader and head of the Islamist-rooted Justice and Development Party (AKP) has been an ardent critic of the new Egyptian government, but recent comments he made linking Morsi's overthrow to Israel have been called anti-Semitic.
Around the world, other supporters of the pro-Morsi camp have also picked up on the symbol.
According to a report on the website of Al-Arabiya television, activists recognizing that the symbol sprang from the violent crackdown on the pro-Morsi sit-in have tried to avoid comedic use of the sign and it is often juxtaposed with the imagery of tragedy.
But anti-Morsi activists and supporters of the interim government have taken to satirizing the symbol -- some in a way that derides the Muslim Brotherhood's Islamist ideology as extreme.
According to official figures, nearly 1,000 people have been killed across Egypt since the breakup of the sit-ins last week. Top Muslim Brotherhood leaders have been arrested on terrorism-related charges, while demonstrators have accused the provisional government of trying to reestablish a military dictatorship.
-- Glenn Kates