Polyaxial bone anchoring device, comprising: a bone anchoring element (1) including a head (3) and a stem (2)； a housing part (5, 5 ', 500) to house a rod (100) in order to couple the rod to the bone anchoring element； the housing part (5, 5 ', 500) comprising an upper end (5a) and a lower end (5b), a first pass (51) coaxial with a first longitudinal axis (51a) and a second pass (56) coaxial with a second longitudinal axis (56a), the first and the second longitudinal axis cutting each other； the first step (51) including a seat (62, 63； 92) that opens toward the lower end (5b), and the seat being configured to allow rotation of the head relative to the seat； and where the head (3) can be inserted into the seat (62, 63； 92) from the lower end, where the seat (62, 63； 92) is essentially symmetrical with respect to the rotation of the head when the head rotates in any direction and in the corresponding opposite direction, and where the seat (62, 63； 92) further comprises a compressible wall (62, 65； 83a) surrounding at least a part of the head (3) to immobilize the head； and where the head (3) has a spherical outer surface part that includes a maximum diameter (E) of the sphere and in which the seat (62, 63； 92) has an essentially concave surface part (63； 92) adapted to engage at least the outer surface portion of the head that includes the maximum diameter.Dispositivo de anclaje óseo poliaxial, que comprende: un elemento de anclaje óseo (1) que incluye una cabeza (3) y un vástago (2)； una pieza de alojamiento (5, 5', 500) para alojar una varilla (100) con el fin de acoplar la varilla al elemento de anclaje óseo； comprendiendo la pieza de alojamiento (5, 5', 500) un extremo superior (5a) y un extremo inferior (5b), un primer paso (51) coaxial con un primer eje longitudinal (51a) y un segundo paso (56) coaxial con un segundo eje longitudinal (56a), cortándose entre sí el primer y el segundo eje longitudinal； incluyendo el primer paso (51) un asiento (62, 63； 92) que se
