And the mine water he drank tasted like machine oil.
In the dark inferno of Earth's belly, he and 32 other miners resigned themselves to die but battled for life.
"We were waiting for death because our own bodies were eating themselves. I was afraid I would never meet my son," Villaroel says.
Now, at a field hospital in the middle of the Atacama Desert, where all 33 rescued miners were brought for care, Villaroel manages to slip a half smile. In his dark, protective goggles and a crisp white T-shirt, he is finally amid joy, unburdened of 69 days of wretched uncertainty.
Husbands in hospital beds kiss their wives. Fathers clasp their children. They relay their 69-day ordeal with the pragmatism of men who have proved their mettle to the entire world.
Villaroel, 27, had been employed two years as a mechanic at the San Jose gold and copper mine in northern Chile. But he never told his mother he was working a half mile under the Earth's surface.
That early August day, everything began shaking. Everything collapsed.
"The mountains and the roof of the tunnel and everything shook," Villaroel says. "The mountain began to break up, and we couldn't see anything, maybe 1 or 2 meters. We drove off in a truck, but we crashed it because we couldn't see anything."
Luis Urzua, the shift foreman, gave his men the bad news straight. They had a chance at survival but it was more likely that they would never see daylight again.
"We had a boss who every day said we must stay strong," Villaroel says. "If they find us, they find us. And if not, not."
The men huddled in an area no larger than 165 square feet. Several, especially the younger, inexperienced minders, threw themselves on the ground. They wouldn't get up.
"I realized several companions were in a bad way. Several didn't get up after that first day," Urzua says from his hospital bed.
Rescue teams sent probes down to see whether they were alive. The probes passed them by a long way away. The men lost hope.
"There was only one key," Urzua says. "And even if the truth hurts, you have to say it."
After that, Urzua says the key became making democratic decisions under trying circumstances.
"We took a vote on everything. As long as we had 17 plus one, well that was the majority."
Every situation was analyzed. What was possible to do? What can we not do? How should we distribute the food?
Most decisions were unanimous.
Everyone was given a job to do. Nobody was left alone. They functioned like a family -- a mix of love, dependence, frustration.
But there were never thoughts on turning on each other, not even when rations quickly began running out.
"We never talked about that but when everything passed, it became a joke," Urzua says. "But at the time, we never thought about cannibalism."
They survived like that for the first 17 days, cut off from a world that had given them up for dead a half a mile under the Earth's surface.
After that, rescuers were able to dig boreholes that became like umbilical chords to the trapped men. Round the clock, rescuers dropped metal cylinders, dubbed "carrier pigeons," down the boreholes taking food, water, clothes and letters to the miners.
That's how the 33 miners survived for 69 harrowing days, until they were all successfully lifted to freedom earlier this week.
In the pristine white of the field hospital, the miners' dark journey seems a lifetime ago. And fresh, like it still is.
They let half smiles slip from their faces. True grit brought them back to the ones they most love.
Raul Bustos to his wife, Carolina. He knows life will be different from now on.
Ariel Ticona to baby Esperanza. Her name means hope in Spanish. Appropriately, she was born while her father had been underground on the verge of losing hope.
The 54-year-old foreman says his men had to do what was possible. But they did the impossible. They survived.
And as the president of Chile said, for Urzua, who chose to be the last rescued from the mine, a very tough shift was finally over.