The Apollo missions brought back moon rocks to Earth. Some of the moon rocks Apollo 11 and Apollo 17 brought back were gifted twice by President Nixon to 135 countries. In the Netherlands, both of these gifts are intact and preserved in a museum. However, there is another unrelated gift, in the form of petrified wood that was mistaken to be a moon rock for several years.
Flat-Earthers use the petrified wood incident to discredit the Apollo missions. In reality, the incident is not related to the two moon rocks that the United States officially gifted to the Netherlands, which are still displayed in Museum Boerhaave, Leiden.