It may look like a piece of obsidian rock, but its Ruffwear Gnawt-a-Rock a durable throw toy 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 its mind.