(Chapter 15) Footnote 72:

The Greek, which Vesalius’ explanation suggests he did not understand, means “wheaten” or “wheatlike” because it tapers like a grain of wheat. The comparison was applied to the odontoid process by Palladius (6th cent. AD) Comm. in Hipp. lib. sextum de morbis popularibus 2.192.12 and Theophilus Protospatharius (7th AD) De corporis humani fabrica 5.4.20. In the 1555 edition, Vesalius adds a comparison to an olive pit.