Zoo Med Excavator Clay Burrowing Substrate - 20 lbZoo Med's new Excavator™ Clay Burrowing Substrate allows reptiles to dig tunnels and burrows just like they do in nature. Watch your reptiles perform natural digging behaviors; mold and create multi-level terraces and burrows in your reptiles terrarium Make your reptiles feel like they are "at home" in their natural habitat. Excavator™ holds its shape so burrows and tunnels won't collapse All Natural! No added dyes, colors or chemicals.