But for all their spiritual resonance, these wafers are also totally mundane. They're made simply by heating unleavened flour and water between two iron plates. And they're so ubiquitous that most Catholics never even question their origins—they seem to just magically appear on the altar.

For Catholics , hosts are potent manifestations of faith. The crackers consumed during Communion are part of a ritual that goes all the way back to the Last Supper. Once blessed, these bits of altar bread are believed to become the body of Jesus, or at least carry his divine essence.

In reality, though, if you're an American Catholic, your communion host likely comes from Cavanagh Altar Breads, a secular, industrial baker.

Based out of Greenville, Rhode Island, the company specializes in mass-produced sacramental wafers. Although they make altar breads for many Christian denominations, they dominate the Roman Catholic Mass market, churning out (according to one oft-reported figure) up to 80 percent of the hosts used by the Church in the US.

It might strike some as odd that intimate, holy objects like sacramental wafers would be mass-produced in a secular facility. Until the late 20th century, priests, members of a parish, or nuns prepared hosts for their community or nearby churches. Cavanagh didn't come into the picture in the US until around 1943, when a Jesuit priest visited nuns making wafers in the Greenville area. He felt their conditions and equipment were miserable, so he asked a local Catholic inventor, John Cavanagh Sr., to help the sisters out. In his life, Cavanagh had developed several new devices, including a patented mechanical stapler and a roofing hammer. To help the nuns of Greenville, he worked alongside his sons to adapt waffle irons and humidifiers to make hosts. Then he created special host-making machines. Three years later, local clergy permitted the Cavanagh family to produce their own altar breads, ostensibly to help the sisters meet expanding regional demand.

For years, Cavanagh just served the New England Catholic community—until the Vatican II overhauled Catholic life in 1962, specifically voiding some old recipes by mandating that hosts be thicker and have a breadier flavor. Its wider adjustments also expanded the market for hosts by making changes that kept Baby Boomers from leaving the Church and helped revive communion rituals in some Protestant communities, who use hosts with different ingredients, shapes, or sizes than Catholics. Protestants didn't have monastic communities to produce hosts for them, while existing capacity couldn't keep up with the expanding Catholic market.