Sessile polyps up to 10mm can often be removed by snare polypectomy.

Adult cnidarians appear as either swimming medusae or sessile polyps.

In contrast, many jellyfish develop as sessile polyps early in their life cycle.

These soon settle and undergo metamorphosis into sessile polyps, known as a scyphistomae, with four tentacles.

The larva develops into the hydroid stage of the life-cycle, a tiny sessile polyp called a scyphistoma.

Surgery is sometimes needed for large colon polyps that have a broad area of attachment (sessile polyps ) to the colon wall.

Sessile polyps larger than 2 cm usually contain villous features, have a higher malignant potential, and tend to recur following colonoscopic polypectomy.

They have two basic body forms: swimming medusae and sessile polyps, both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes.

Polyps that are pedunculated (with a stalk) are usually less dangerous than sessile polyps (flat polyps).

Within the Cnidaria, the Anthozoa (sea anemones and corals) are regarded as the sister-group of the rest, which suggests that the earliest cnidarians were sessile polyps with no medusa stage.

Sessile polyps have a shorter pathway for migration of invasive cells from the tumor into submucosal and more distant structures, and they are also more difficult to remove and to ascertain.