An advantage of colonoscopy over X-ray imaging or other less invasive tests is the ability to perform therapeutic interventions during the test. A polyp is a growth of excess of tissue that can develop into cancer. If a polyp is found, for example, it can be removed by one of several techniques. A snare device can be placed around a polyp for removal. Even if the polyp is flat on the surface it can often be removed. For example, the following shows a polyp removed in stages: