It seems a Dr Howard Lang was in the archives of the British Geological Survey when he found some drawers marked Unregistered Fossil Plants. Inside were hundreds of fossils that have not seen the light of day for a smuch as 165 years. Museum curators soon realized that some of the material was actually collected or analyzed by Charles Darwin himself and during his most scientically formative time; see the piece of fossil wood below found by Darwin in 1834 while sailing on the HMS Beagle, and thinking about how biological diversity could arise over time, an idea he would later call evolution.

(PlanetEarthOnline) — It turns out that botanist Joseph Hooker, long-time director of Kew Gardens and Darwin’s best friend, had assembled the collection at the start of his career during a brief stint at BGS in 1846. Among the specimens were some found by Hooker himself during an Antarctic voyage in 1840. Others seem to have come from the cabinet of the Revd John Henslow, Darwin’s mentor at Cambridge whose daughter later married Hooker. … The collection may have slipped into obscurity partly through bad timing; Hooker had set off on an expedition to the Himalayas by the time BGS’s formal ‘specimen register’ was established in 1848. When he got back, in 1851, the collection was being moved to the Museum of Practical Geology in Piccadilly and the opportunity for him to label the fossils had passed.