カツオノエボシ
The stinging, venom-filled nematocysts in the tentacles of the Portuguese man o' war can paralyze small fish and other prey. Detached tentacles and dead specimens (including those that wash up on shore) can sting just as painfully as the live organism in the water, and may remain potent for hours or even days after the death of the organism or the detachment of the tentacle.