WASHINGTON — Trilobites may be the archetypal fossils, symbols of an archaic world long swept beneath the ruthless road grader of time. But we should all look so jaunty after half a billion years.

At the Smithsonian’s National Museum of Natural History, Brian T. Huber, chairman of paleobiology, points to a flawless specimen of Walliserops, a five-inch trilobite that swam the Devonian seas around what is now Morocco some 150 million years before the first dinosaurs hatched. With its elongated, triple-tined head horn and a bristle brush of spines encircling its lower body, the trilobite could be a kitchen utensil for Salvador Dalí. Nearby is the even older Boedaspis ensifer, its festive nimbus of spiny streamers pointing every which way like the ribbons of a Chinese dancer.

In a back room of the museum, Dr. Huber opens a drawer to reveal a dark, mouse-size and meticulously armored trilobite that has yet to be identified and that strains up from its sedimentary bed as though determined to break free.

“A lot of people, when they see these fossils, don’t believe they’re real,” said Dr. Huber, who is 54, fit from years of fieldwork, and proud that the state fossil of his native Ohio is a trilobite. “They think they must be artists’ models.”