ClipArt ETC
"Nettling cells of Hydra. A, unexploded; B, exploded; b, barbs; c, the nettling cell in which the nettling organ is developed; cn., the cnidocil or "trigger"; cp., the capsule or nettling organ; f, the nettling filament or lasso; n, neck of the capsule; nu., nucleus of the cell." — Galloway

Hydra

"Nettling cells of Hydra. A, unexploded; B, exploded; b, barbs; c, the nettling cell in which the nettling…