Large, egg-shaped vessels have been appearing in increasing numbers at high-end wineries on the West Coast, stirring a mixture of bafflement, warm, return-to-the-womb associations and fears of an alien invasion.
Adding to the strangeness, these eggs—which are about the size of an adult male hippopotamus, with Humpty-Dumptyesque proportions-are concrete: The base material of parking lots and Soviet Bloc architecture, and a throwback to a benighted American winemaking past—the 1940s and '50, when winemakers wore white lab coats, and fermented their juice in thousand gallon, in-built concrete swimming pools—is now a desired material at chichi joints like Screaming Eagle, Rudd, Vineyard 29 and Quintessa.

Not so surprising, says Charles Thomas, the winemaker for Quintessa, and the father of the concrete renaissance on these shores. While traveling through Bordeaux and Burgundy in the 1980s, Thomas noticed something peculiar. The large co-ops making cheap wine in bulk still used concrete—places, he said, that "looked like San Quentin, with wine tanks as cell blocks"— but so did some of France's greatest chateaux, like Petrus and Cheval Blanc.

Those estates had, ahem, concrete reasons: The material is porous, like wood, allowing the fermenting wine to breathe, without imparting the oaky flavors associated with barrels. Also, concrete is "insulative" while stainless steel is "conductive": In effect, concrete acts as a low-tech temperature control, steadying fermentations and helping die yeast avoid choque-thermique (one of those superb Gallic phrases with a meaning exactly as it sounds.) And, not least, concrete is cheaper than both stainless steel and oak barrels.
Which brings us to the eggs. They're made by Marc Nomblot, a Maconnais stonemason whose family has manufactured concrete wine tanks since 1922. (At first, they specialized in mausoleums; then one day, at a funeral, a winemaker asked a Nomblot if he could put a valve on one of the mausoleums.) In 2001, biodynamic Rhone winemaker Michel Chapoutier asked for an egg-shaped fermenter. Not long after, Charles Thomas spotted one of those egg prototypes on the Nomblot factory floor, and soon an egg, along with several concrete fermenters, was sitting in Rudd's Napa Valley cellar, where Thomas was working at the time.

The eggs have been firing the imaginations of West Coast wine-makers ever since. Some, especially those of the biodynamic persuasion, get mystical when describing the egg fermenter. (One Napa winemaker spoke of "an arc of endless energy"; Delia Viader once called it "the most perfect shape in physics. It creates a vortex, allowing us to garnish the fourth and fifth moon cycles.")
These days concrete-—essentially sand, stone and water (Nomblot doesn't use chemical additives)— belongs to a back-to-the-earth movement in winemaking, which shuns the extremes of sterile winemaking for more natural environments and practices that harken back to ancient times. (Sam Tannahill, at Oregon's A to Z Wineworks, originally wanted to ferment white wine in amphoras buried in the ground as the Romans did; the concrete eggs were the next best thing.)

In fact, the eggs have a connection to ancient Greece. Nomblot constructs his molds in adherence to Pythagoras's golden mean—the mathematical ratio used, for example, in the pillars of the Parthenon.
Glimpsed in situ, the eggs function as a sort of three-dimensional, otherworldly Rorschach test. For Trevor Dorland, the general manager of Cayuse Winery in Walla Walla, Washington, it's pop culture: "Mork and Mindy. You expect Robin Williams to pop out." One winemaker confessed-—off the record—the eggs reminded him most of Fat Man, the atomic bomb the United States dropped on Nagasaki. But when Tannahill took his three-year-old son, Theo, to his winery, Theo saw the concrete oval fermenter and said, "Oh, look, it's an egg!" Then he ran up and hugged it.