A block used to construct a wall. The block has a front and rear surfaces, top and bottom surfaces, and side surfaces. The bottom surface of the block has a projection that extends downwardly therefrom and which is configured to engage one or more blocks in an adjacent course of blocks to prevent movement...http://www.google.com.au/patents/US7207146?utm_source=gb-gplus-sharePatent US7207146 - Multiple purpose wall block
