French illustrator Jean Jullien's unifying symbol for peace shared worldwide

(CNN)Before the names and faces of the victims of Friday's terrorist attack in Paris emerged, there was one unifying symbol.

A simple image shared by millions across social media: the combination of a peace sign and the Eiffel Tower.

Jean Jullien, the 32-year-old French graphic designer behind the image, posted it onto his Instagram and Twitter on Friday, soon after a series of terror attacks in the French capital -- since claimed by ISIS -- left 129 people dead and 352 injured.

Full coverage of Paris terror attacks

"It was the most spontaneous thing. I heard the news on the radio, and I had this heartfelt reaction. I wanted to draw something that could symbolize peace and solidarity, and I wanted something with the context of Paris," Jullien tells CNN.

'Peace for Paris' appears around the world

Besides social media platforms, Jullien's illustration is being used in a public show of support -- hand-drawn onto posters, shirts, and in other ways of commemorating the victims. Photos from around the world have captured people using the sign.

"The response has been overwhelming -- especially since I didn't have any control over it. But I can't feel pride or happiness because it is such a dark time. It's undesired exposure. A horrible moment. But, I'm just somehow glad people made use of it."

"Words can sometimes be difficult to translate. I think the simpler, the better, the more universally understood it can be."

Jullien runs a studio in London, where he is currently based. His practice includes illustrations, photography and moving image.

Charlie Hebdo response

While he doesn't often engage in politics in his work, an illustration he created earlier this year, was also widely shared.

This image, a pencil facing off with the barrel of a gun, was a response to shootings at the offices of French satirical newspaper, Charlie Hebdo, in Paris earlier this year.

"At the time, it was the same. Illustration is my job, and it's my only way of expressing myself."

Some interpret base of Eiffel Tower as cross

Thousands on social media, says Jullien, have pointed to the base of the Eiffel Tower in the 'Peace for Paris' symbol, and asked him if it's the depiction of a cross.

Jullien says he didn't intend for that.

Eiffel Tower closed, travel plans impacted by Paris attacks

"That's the beauty of an image, people can see what they can see. And if it helps with their faith, than I'm fine with that. But it wasn't designed this way. What I hope is that in the wake of tragedy, there is a symbol of peace, unity and something positive. Instead of just anger, there is hope."