Sessile polyps develop on the mucosa, the tissue that lines the colon and other organs. They are flat and round and mostly harmless, but some can become cancerous. Polyps can be peduncled or sessile.

Polyps are tissue growths that most often look like small, flat bumps or tiny mushroom-like stalks. They are usually small and less than half an inch wide. Most are benign but can become cancerous.