He was the youngest of the 50 victims in the attacks.
"He could have grown up to be a brilliant doctor or the prime minister," said Mohamud Hassan, a 21-year-old member of the Christchurch Somali community, which comprises about 60 families.
He shook his head, an expression of the common refrain after all mass shootings: "Why?"
Mucaad's father, Adan Ibrahim, had collected him at around noon on Friday to take him to Friday prayers as usual.
After prayers, the young men often went to play football in Hagley Park across the road, and Mucaad often went with Abdi to watch.
But on Friday, when the gunman stormed into the mosque about 10 minutes into the sermon and started spraying bullets indiscriminately around the men's section, little Mucaad appeared to think it was a scene from the kind of video game his old brothers liked to play.
He ran toward the gunman, Hassan said. Amid the chaos, his father and brother ran in different directions.
After the carnage had ended, a worshiper carried him to the arriving medics.
On Sunday night, Mucaad's father was waiting at the hospital, hoping to see his smallest son for the first time since he was killed.
"He's been loved by the community here," said Ahmed Osman, a close family friend. "It's been tough days. It's been really tough days."
The toddler impressed Osman with his intelligence and seemed particularly to enjoy talking to older people.
On Sunday, Abdi Ibrahim waited at Christchurch airport for the arrival of another brother, Abdifatah Ibrahim, who had been overseas when the massacre occurred.
The shooting, Abdi said, still felt like a terrible dream.
"My mum, she's been struggling," Abdi said. "Every time she sees other people crying, emotional, she just collapses."
A few minutes later, Abdifatah emerged through the arrivals gate. He and Abdi wrapped their arms around each other in a tight embrace.
And then they went to wait for the release of their little brother's body so they could lay him to rest, a life ended before it had barely begun.
- Washington Post/AP