It may look like a piece of obsidian rock, but it’s Gnawt-a-Rock – a durable throw toy is inspired by natural volcanic glass formed by rapidly cooling lava from Pacific Northwest volcanoes. The Gnawt-a-Rock is made with natural latex rubber, a faceted surface, and an irregular shape. It all comes together to keep your pup guessing, whether chasing after its erratic bounce or nuzzling and nosing it around for interactive treat-dispensing to stimulate their mind. Check out the Gnawt-a-Stick™ and Gnawt-a-Cone™ - the other two toys in the Pacific Gnaw-west toy collection inspired by the natural surroundings in Ruffwear’s home of Bend, Oregon. One Size: 4.5 in (11.5 cm) Diameter Our toys are designed to be interactive – it's just more fun that way. While our toys suit a range of play styles, dogs can be crafty and determined chewers, so supervised play is recommended. If any part of the toy becomes loose or detached, take the toy away and discard.