Kyte was examining sediment cores drilled from the Pacific just north of Hawaii. Unlike most other marine sediments, those from around the time of the impact are bereft of microfossils--their absence marks a planetwide disaster. In one of the core samples, which were mostly fine-grained sediments, Kyle spotted something unusual. "I saw this little rock in the core," he says, "and I plucked it out."
The rock turned out to contain a 2.5-millimeter-long fragment of an asteroid. The texture of Kyte's rock, and the high concentration of iridium, chromium, and iron, suggested that it came from an asteroid and not a loose, sooty ice ball like a comet. "We probably have," he says, "a piece of the object responsible for one of the worst days in the history of Earth."