A sealing element (10) of a deformable material for sealing an opening in a wall (16), which separates two different chambers, comprises at least one aperture (12) which is arranged in a sealing first region (20) and is designed to receive a tube (14), and a yielding second region (24) which is designed to be pressed against the wall (16), wherein the second region (24) is differentiated from the first region (20) at least in part by an indentation (22).