One of the rarest and most sought-after fruits, the Australian finger lime, has started showing up in significant quantities at the Santa Monica farmers market, creating a minor sensation. The fruit's appearance is enough to excite wonder: from the outside it looks like a little gherkin, but when sliced in half, the round, pearlescent juice vesicles ooze out of the fruit, like citrus caviar. The clean, fresh, tart lime-lemon taste is enticing enough, but the texture, crunchy and juicy, like citrus Pop Rocks, is even more prepossessing.

"This is so cool. I'm really excited," said Evan Funke, chef at Rustic Canyon, fascinated by the translucent drops. He was among the crowd of chefs, purveyors and regular market-goers who clustered around the Shanley Farms stand at last Wednesday's market, as Jim Shanley of Visalia and his daughter Megan explained what the fruit is and how to use it.

One of a half-dozen species of Australasian citrus, the finger lime is native to the rain forests of eastern Australia. It is not directly related to familiar Bearss and Mexican limes. Although the species was first brought to the United States more than a century ago, only in the last six years have disease-tested, legal budwood became available to nurseries for propagating the trees, and farmers started commercial plantings. In California, about 40 acres have been planted, or will be shortly; of those, perhaps only a third have started to bear.

The best way to use the fruit is to cut it in half and squeeze out the juice vesicles, like pushing toothpaste out of a tube. The rind is thin and edible in theory but too tough to be pleasurable to eat, though it can be used in marmalades or as a garnish. As with other acid citrus, finger lime pulp is mostly too sour to eat fresh by itself. But it is used as a garnish, in upscale cocktails, on persimmons and as a counterpoint to seafood (it's great on oysters). Josiah Citrin of Mélisse says that he is using finger lime caviar in a red miso vinaigrette with hamachi poisson cru.

Commercial production, in tiny quantities, began just last year. Demand far exceeds supply, so prices are high for now. Both the Shanleys, who have 1,500 finger lime trees, and Mud Creek Ranch of Santa Paula, which has just 12, were selling the fruit last Wednesday for $10 in half-pint plastic clamshells, roughly 6 ounces each. That's not cheap, but a little goes a long way. For the skeptical or frugal, the Shanleys also sell individual fruits for 50 cents.