 I knuckles the echidna, but you can call me knuckles. I have a single opening called a cloaca. Eggman is after the master emerald. I excrete both feces and urine out of my cloaca, which is my single opening. I broke the master emerald into pieces to stop Eggman from taking it. Cloacas are more common than you think. All amphibians, reptiles, and birds have them. People ask where I keep the shards of the master emerald. I keep them in my cloaca.