Is this normal for clay? I was under the impression it needed to be fired to become solid like that. The reason I ask is I have a partly demolished wall that I would like to restore, and I am thinking that perhaps I could just excavate this area of the garden to use as a building material, rather than try to solve my drainage problem. If this is not normal for clay, how could I identify what it might be, and if/how to use it as a building material? If I can make a cob from this, would that be suitable for an outdoor wall?