Geography cone, Conus geographus Because all Conus snails are venomous and capable of "stinging" humans, live ones should be handled with great care or preferably not at all. The species most dangerous to humans are the larger ones which prey on small bottom-dwelling fish.
The Stonefish. This gill-ed underwater critter holds the title for the MOST venomous fish in the world, calling home to the Great Barrier Reef where it lives on the sea floor, disguised as an encrusted rock.
Scorpaenidae, the scorpionfish, are a family of mostly marine fish that includes many of the world's most venomous species. As the name suggests, scorpion fish have a type of "sting" in the form of sharp spines coated with venomous mucus.(via Wild Eye Images)