Nematocysts are found in coelenterates.
Nematocysts are specialised stinging cells that serve as defensive and offensive organs in Coelenterates. They are specialised cells known as cnidocytes that are altered epidermal interstitial cells, that contain cell organelles. Except for the basal disc, nematocysts can be found all over the surface of the body. They can be found in large numbers on the tentacles and hypostome.