The invention relates to an ear tag (1) for tagging animals, which ear tag (1) comprises:- a housing with a first housing shell (2), a second housing shell (3) and a through hole (4) extending through both first and second housing shells- a mandrel plate having a back plate (6) and a mandrel (7) extending substantially perpendicular from the back plate (6), wherein the tip of the mandrel (7) has a bulgewherein the outer shape of the housing is plane symmetric along a symmetry plane substantially perpendicular to the longitudinal axis of the through hole.
