University of California, Berkeley, graduate student Allen Liu last Friday donned coveralls, a blindfold, earplugs and gloves, then got down on all fours and sniffed out a 33-foot chocolate trail through the grass.

Ever since NASA's Stardust spacecraft delivered a payload of comet dust to Earth on Jan. 15, 2006, scientists by the hundreds have been clamoring for samples.

In the storerooms of a Venice, Italy, museum, a University of California, Berkeley, scholar and Italian experts are at work on a rare collection, but the objects aren't Renaissance paintings or the art of ancient glassblowers.