Tooth of a predatory marine snail
The predatory marine snail Conus ermineus lives in a shell between 2-4 inches in length. Like the barrel of a gun, Conus snails possess a battery of venom-loaded, harpoon-like teeth located within their throat with one tooth “loaded” and ready for use. When prey is detected, the snail rapidly fires the tooth and injects a potent cocktail of neurotoxins that paralyzes small fish almost instantly. The snail then retracts the tooth, reeling in the prey before swallowing it whole. Conus snails can fire these venomous harpoons in any direction (even backwards), and some of the loaded toxins can be fatal to humans.
Image by Dr. Alan Kohn and Dr. Joshua Kubo, University of Washington.