When travelling down a sand dune, the Saharan rolling spider (Araneus rota) is capable of rolling on its outstretched legs, achieving speeds of over 4 mph. It looks "like a small, unusually fast tumbleweed."- via spiegel
I don't mean to discount the neatness of this, which is secure, but the german narrator comments that the spider stands as disproof of the statement that the wheel does not instantiate in nature, and if it's rolling like a ball, other instances come to mind: spherical seedpods 'designed' to roll away from parent trees, etc. I wouldn't be surprised if another reader can think of a true wheel in nature as well. The biochemical mechanism of the flagella 'hub' comes to mind as an iffy candidate.
I don't mean to discount the neatness of this, which is secure, but the german narrator comments that the spider stands as disproof of the statement that the wheel does not instantiate in nature, and if it's rolling like a ball, other instances come to mind: spherical seedpods 'designed' to roll away from parent trees, etc. I wouldn't be surprised if another reader can think of a true wheel in nature as well. The biochemical mechanism of the flagella 'hub' comes to mind as an iffy candidate.