Colorectal polyp. Combined coloured computed tomography (CT) and 3D CT scans of the colon (large intestine) of a 62-year-old male patient, showing a polyp (small, round). Polyps are benign (non-cancerous) growths that arise from mucous membranes. Although benign, polyps are generally removed surgically as their growth may obstruct the passage of food and some polyps may turn cancerous over time.