 Their main tunnels are used for feeding and for escape : they can dig themselves underground very rapidly , and can move along existing tunnels at high speed both forwards and backwards . Their digging technique is to force the soil to either side with their powerful , shovel @-@ like forelimbs , which are broad , flattened , <unk> and heavily <unk> ( the <unk> is hardened and <unk> ) . 
