Rocks Homemade RattyRat's Review: Some rats go bonkers for rocks, some don't. That's why we went with 3 paws. They like to smell the smells from outside on them. Bring in some large rocks that they can climb on, and perch on top of. Get some small rocks that they can carry around. Make sure the rocks have nothing toxic on them. One thing that is fun is to buy some polished rocks from a craft store and put them in some shallow water for the rats to play with.