Abstract: A vivarium wall device system comprising: a piece of coral or a piece of wood, the piece having a glass-side surface, upper surface, lower surface, and three side surfaces, and where the glass-side surface is generally flat and regular; a vivarium wall attachment means comprising: a first inside magnet, generally permanently attached to the glass-side surface; a first outside magnet, configured to be removeably and magnetically attachable to the first inside magnet; where when the first inside magnet is configured to be located inside the vivarium and magnetically attach to a first outside magnet located outside of the vivarium, and where the magnetic attraction occurs across a vivarium wall, and the coefficient of friction of the vivarium wall and the magnetic force tend to hold the piece of coral in place on the vivarium wall.