A rubber shock absorber for a mooring guard comprising a hollow rubber element of revolution having a generally truncated conical shape adhering to a base plate with an angle of inclination A of its conical wall in the order of 60.degree. - 85.degree.. The rubber element has a hollow section with an axial length H and a conical wall with a radial thicknes E so dimensioned that the outer diameter D of the small base of the rubber element at right angles to the hollow section is substantially equal to the inner diameter d of the large base of the section. In this arrangement, the conical wall of the rubber element operates essentially through bending and extension towards the outside under a crushing stress comprising an axial component and provides lateral stability to counteract the tangential components of this stress.