JERUSALEM, Israel - Zeev Portenoy was nine when the Nazis invaded Tuchin, his Ukrainian hometown, in 1941, forcing his family and the other Jews into a ghetto while he went on the run.
For the next four years, he wandered aimlessly around the countryside, pretending to be Ukrainian or Polish just to survive. He knew he was Jewish but just didn't understand why everyone wanted to kill him, writing down his experiences in a song.
"There was this fear that one day they would find me so I kept the song on me," he said.
"I put the song inside one of my long boots so that if they caught me and killed me, somebody would find the song." Now in his 80s, his voice breaks as he sings the words he wrote as a child: "I was still a small lad / when the Nazi beast / took over my life / And took me away from / My parents forever." He survived the genocide. But 1.5 million other Jewish children did not.
Their stories are the focus of a new exhibition at Jerusalem's Yad Vashem Holocaust museum which opened ahead Israel's Holocaust memorial day which starts at sunset on Wednesday.
Entitled "Stars Without A Heaven" the exhibit gives expression to the lives of children during the Holocaust through a "symbolic forest" of 33 pillars, with each bearing a different personal story along with pictures and testimonies, but also small sculptures and short animated clips that illustrate lives where no memento remained.
"The world of the child, the humanity which is expressed through their creativity, their thoughts, is this forest... a forest of young souls," said Yad Vashem chairman Avner Shalev.
Yehudit Inbar, the exhibition's curator, said there were very few mementos of the lives of the 1.5 million who perished - about the same as the number of children living in Israel today.
"If the adults thought they understood what was happening, the children didn't understand the situation at all," she said.
Teddy bear hero
At the entrance is a long showcase inside which are dozens of worn teddy bears and dolls with china faces from the 1930s and 40s.
This is the world's largest collection of surviving Holocaust-era toys.
"It sounds like a lot but if you think that each child had a toy - a doll or a teddy, or a small wooden toy - and then think that there are less 50, then you realise how many didn't survive," Inbar said.
One of the bears belongs to Inna Rehavia, who was born in Krakow and was saved along with her mother by two Polish families.
"I went through the whole war with my teddy bear. He's called Mishu and I got him when I was born. He was with me through the war, passing from one ghetto to the next," she told AFP.
"The bear survived better than me and better than many people. Although he became disabled in the war. He's missing an ear and an arm. He was still a great hero." A series of drawings in coloured pencil tells the story of Stefan Cohn who was 14 when he was forced to work at the bricklaying factory in Auschwitz-Birkenau.
He survived, drawing detailed pictures of his experience when the camp was liberated in 1945.
Where there is no memento, small sculptures help tell the stories.
A tiny white ceramic bookcase illustrates that of a Polish boy called Jakov Goldstein, who was four when the war began, and spent more than two years hiding in a tiny cramped attic of a local family.
"My only consolation through this long dark period was books. If it weren't for my incessant reading there is no doubt I would have become 'brain dead' or even worse," says a snippet of his testimony.
'I didn't understand'
Martin Weyl was only four when he was sent to Theresienstadt concentration camp in what is now the Czech Republic.
While he was there, the camp was smartened up for a Red Cross visit as part of a Nazi propaganda effort to portray the camps as model settlements.
"They came in a jeep with a red cross on it and I as a child was very impressed by this jeep and made a drawing of it," he says, pointing to a yellowed reproduction of his picture.
"I didn't understand anything - I was a child." Small children were largely left to their own devices, finding whatever they could to play with.
"I remember playing on the garbage dump in the camp. We would take a piece of glass and when the sun shone we would try to burn the garbage," said Weyl, 75.
He said the post-war period was as frightening as the war itself.
"All the grown-ups were traumatised and that influenced the children." Weyl's childhood was dominated by World War II and its aftermath, leaving him with "a constant, existential fear".
"It's particularly common to people who were in the Holocaust. Existential fear is something which doesn't ever leave me."