Cone snails deliver venom through a hollow, barbed tooth fired from an extensible proboscis. The geography cone adds a second stage. It first extends a wide, funnel-like rostrum over a sheltering fish and expels a chemical cloud into the surrounding water, a strategy sometimes described as a nirvana cabal.
Among the components of that cloud is a specialised insulin. Reported in 2015, the peptide is unusually small and closely resembles fish insulin rather than the snail's own. Taken up across the gills, it drives blood glucose down and produces hypoglycaemic torpor, so the fish is already impaired when the harpoon lands and the paralytic conotoxins follow.
The venom is genuinely dangerous to humans, and confirmed deaths from Conus geographus stings exist, though they are rare and involve handling live animals. The much-repeated claim that there is no antivenom is accurate; treatment is supportive. What is frequently exaggerated is the number of deaths, which is on the order of a few dozen recorded cases historically rather than the hundreds sometimes cited.