What is the X in X-mas?
nematocyst nem·a·to·cyst (něm'ə-tə-sĭst', nə-māt'ə-)
A capsule within specialized cells of certain coelenterates containing a barbed, threadlike tube that delivers a paralyzing sting.
One of the minute capsules in the tentacles of cnidarians, such as jellyfish, hydras, or sea anemones, used for stinging. The capsule is produced by a special cell (called a cnidoblast) and contains a tightly coiled barbed thread that quickly shoots forth if the capsule's lid is disturbed. The thread often contains poison.
minute, elongated or spherical capsule that is found chiefly in members of the phylum Cnidaria (e.g., jellyfish, corals, sea anemones). The capsule, which occurs on the body surface, is produced by a special cell called a cnidoblast and contains a coiled, hollow, usually barbed thread, which quickly turns outward (i.e., is everted) from the capsule upon proper stimulation. The purpose of the thread, which often contains poison, is to ward off enemies or to capture prey.