At the beginning of March, an anonymous philanthropist offered 300 euros ($320) in cash and a camping trip for two, all hidden around a big fashion store at a Frankfurt market. HannsM's 1,000-odd followers on Twitter kept their eyes peeled for photographs or any information that the mysterious benefactor would reveal about the whereabouts of the buried money.

Eager cash hunters found 50 euros, sometimes rolled up inside a beer bottle, sometimes hidden under the grass and sometimes behind steel rails marking the boundary of the Italian consulate in Germany's finance capital.

Every now and then, participants found pictures of themselves searching for cash and realized that the elusive HannsM was actually somewhere close by, watching them as they greedily hunted for extra pocket money and free summer trips.

"Then I put in some photographs of African refugees trying to cross into Europe from Morocco or Spain, followed by pictures of defectors from the former East Germany," says Zerai Kiros Abraham, who has just reluctantly exposed himself as the man behind HannsM's giveaways.

Zerai, as he is known among friends, heads an initiative called Projekt Moses, which aims to integrate African refugees into German society and to foster understanding about migrants who have often fled war, famine or political oppression.

Why a treasure hunt?

The treasure hunt was an idea that Zerai and his friends got from the Hidden Cash movement in San Francisco, founded by Jason Buzi and Yan Budman, who hid stashes of money in different locations, bought groceries and sponsored free food with the intention of "fun and giving."

"We simply turned the game around," says Zerai, in his mid-thirties. "Hundreds of people came for the treasure hunt," he adds. "Even the police were there because there were so many people ... searching for money. And I thought, 'Look how these people are crazy about cash.' It's just the same as Eritrean or African refugees. They are not looking for extra money, they have to secure their existence."

Zerai and his colleagues were trying to show people that human beings all over the world would jump fences and climb over walls for a couple of euros and that migrants who were trying to escape oppression were just the same.

No place for prejudice

Projekt Moses has adopted one of East Germany's most famous fence jumpers as its icon: a soldier called Hans Conrad Schumann. The young conscript, who was posted in Berlin in 1961 during the construction of the wall, jumped over the barbed wire into West Berlin one day. An image of him springing over the fence has become a symbol of the Cold War era, along with the images of thousands of East Germans who camped at West Germany's embassies in Budapest and Prague in 1989.

"There is a verse in the Bible," Zerai says, paraphrasing Exodus. "God tells the Israelites, 'Do not forget that you were refugees and foreigners ... and even slaves."

Zerai has used historical incidents as themes for his cash-hunting events inside the Italian consulate, where people climbed over rails to find hidden money. And, once, to get the treaure hunters to focus their thoughs on Africa, he buried money under the banks of a small pond across Frankfurt's landmark trade fair tower. Money hunters braved subfreezing temperatures to dive into the pond and win 50 euros - signifying the hundreds of war-weary travelers who cross the Mediterranean on flimsy boats to reach safer shores.

At the end of 2014 - a year in which the government approved more than 200,000 applications for asylum - the PEGIDA movement broke out in Dresden, in the former East, protesting the perceived "Islamization" of Germany and Europe. PEGIDA's stated motivation and the country's accepting such a large number of applications for asylum have contributed to the ongoing debate over the cultural and financial impacts of mass immigration.

'Refugee' is relative

Zerai wants the German community to acknowledge the odyssey that migrants make in their quest to find a safer place - "from Eritrea to Sudan to Libya and then over the Mediterranean to Italy and then to Switzerland or Germany or even Norway," as he puts it.

"These people have earned respect and they should be held in high esteem," says Zerai, who came to Germany 15 years ago. "I try to not identify with the word refugee," he says, describing how his Eritrean family managed to pay for a flight to Germany. "If I am a refugee," he says, "then what would you call people who pay a heavy price and undertake a long journey to come here?"

For Zerai, a refugee must, at some point in time, do away with the label. Some of his proteges have even contributed money to the Hidden Cash program. "It was Petros' way of saying thanks," Zerai says, citing the example of a fellow Eritrean.

The activist is busy trying to help Eritreans who live in Frankfurt make their integration into German society easier. His latest project is called Ubuntu cafe, a "hip and stylish" place for people to meet and get to know each other - without any prejudices and without worrying where they come from.