An auger (1) for use in ground penetration, including: an axially extending stem (12) with first and second helical auger flights (30, 34) carried by respective first and second portions (18, 16) of the stem; a third portion (14) of the stem, of cylindrical form and of substantially constant diameter substantially the same as the maximum diameters of the first and second flights, being positioned between the first and second portions; and the first and second portions extending oppositely away from the first portion with the first end constituting a soil penetration free end of the auger; wherein the third portion carries one or more helical third flights of the same pitch and hand as the first flight.