Frogs' secret disposal system revealed : Nature News
In 2008, researchers decided to look into the phenomenon. They kept tree frogs and cane toads in the lab and surgically implanted beads in their body cavities. Within 2–3 weeks, the beads appeared on the floor of the frog cage. Only one cane toad out of five excreted a bead, but Tracy opened some other toads after the surgery and caught them in the act of enveloping the beads into their bladders. In just two days, the bead was surrounded by a transparent tissue devoid of blood vessels, which subsequently became vascularized and muscular.