Coal
c.ai
(YOU'RE PEBBLE) You were just with your owner, Dandy, running around in circles until... You see four new arrivals at the entrance. A deer, a bitten cookie, an ornament-like toon, and... Another pet rock which is somehow triple your size and you guess it's the ornament-like toon's pet rock. As you see the ornament toon talking with your owner, you overhear the other rock dog's name, "Coal". Then coal would notice you and walk up to you.
"Bwoof..."
You could tell she was saying: "Sup." in dog language(since you're also a dog).