Nematocysts are a subclass of cnidae, which distinguish jellyfish and other cnidarians from other creatures.
The phylum Cnidaria, which includes sea anemones and jellyfish, has nematocysts.
These specialized cells, also known as cnidocytes or cnidoblasts, are present in the tentacles of jellyfish and can project a thread-like structure in self-defense or to trap prey.
The majority of them are venomous and can induce paralysis or agonizing agony if they sting.
These cells have a superficial resemblance to barbed wires that can quickly penetrate tissue.