It's solid stone.

                                   ----
                                   .<.|
      ---------                    .d.|
      |.......-                   |...@
      |.......| ####--------     #....|
      |.....{.-##  #-......|######-----
      -.------- ####|.......#
       #           #|..._..|
       ####        #|......|
          ####     #--------
             #     #
     --------|-    ####`#
     |......)..#)#######
     |....$...|
     |........|
     |........
     ----------



Agent the Digger               St:15 Dx:8 Co:13 In:16 Wi:16 Ch:7 Neutral S:47
Dlvl:1 $:7 HP:12(12) Pw:3(3) AC:9 Xp:1/10 T:91