"Untreated wood" refers to wood that has not undergone any chemical or protective treatment to prolong its durability or protect it from decay, insects, or weathering. Full definition
Don't forget to put a hamster wheel or other toys, like a piece of untreated wood for the hamster to chew on, in their cage. (wikihow.com)
Other toys can include untreated wood products, hard plastic baby toys, plastic balls with bells inside, pine cones, oatmeal boxes, and phone books. (myhouserabbit.com)
Speaking as a nutritionist, my best advice is to save your money and show your love with healthy treats like vegetables, hay and untreated wood for chewing. (houserabbitga.com)