A bullet-resistant armor element for use as a tessellation in a flexible armor matrix has a hard main body and a facing over said main body, such as layer of polymeric or polymer matrix composite material, wherein the facing has an acoustic impedance which is substantially lower than the acoustic impedance of the main body. Groups of said elements tessellate to form an aperture between the adjacent elements, and a cover element is arranged to cover said aperture. Limit stops restrict the degree of articulation between the adjacent elements. The elements include a deflector for deflecting bullet splash and traps for collecting bullet splash.