An artificial underwater memorializing catacomb and reef system and evocative environment for a visitor is made from one or more urns containing cremated remains imbedded at least partway within a plurality of concrete forms, whereby the concrete forms are interlocked and/or stacked to form the catacomb. One or more urns containing cremated remains is then interposed at least partway within the molds before the mixture sets, thereby forming one or more concrete forms when the mixture sets. A single module reducing beach erosion and providing a marine habitat includes a base portion, a middle portion having a flange, and an upper portion having an interior void and holes in the sloping sides. One or more urns are placed within reinforcing bars in the base and middle portions.