Some useless / educational info!!!!
Nematocysts, or stinging cells, are used by jellyfish to deliver toxins into their prey. The stinging apparatus consists of a "harpoon" on a thread coiled inside the stinging cell, and attached to a reservoir containing venom. On contact with the victim, the stinging cell discharges its harpoon into the skin and injects venom. Each tentacle may be covered with millions of stinging cells, resulting in a large amount of venom being injected over a wide area.

Watch out for Chironex fleckeri!