An implantable prosthesis can be formed from an improved biocompatible material that provides for cellular colonization of the biocompatible material. Specifically, the biocompatible material is a rigid porous material. In embodiments of particular interest, the implantable prosthesis is a mechanical heart valve prosthesis with a rigid occluder. In some embodiments, the rigid occluder is formed from the biocompatible material. A filler comprising a hydrogel or a structural protein can be located within the pores. In some embodiments, a bioactive agent is within the pores. In some embodiments, the rigid occluder is formed from a polymer material, a carbonaceous solid or a ceramic material. The pores can extend through the rigid material.