Exo Terra Small Moss Mat Terrarium Substrate. The Exo Terra Moss Mat is an extremely natural-looking terrarium substrate that can be used for all types of reptiles and amphibians. Soft, hygienic and absorbent, the Exo Terra Moss Mat is easy to use and can be cut to fit any terrarium size. Simply rinse clean when soiled or replace as necessary. Natural look Hygienic substrate substitute Easy to use Soft & non-abrasive Absorbent & washable Available Size: 45 x 45 cm (18" x 18")