The African giant snail is generally considered to be the world's largest land snail; it can reach a length of 20 centimeters, or about 8 inches. The largest marine snail species is the Australian trumpet, which can reach a length of 91 centimeters, which is over 36 inches.
The African giant snail is a highly invasive species that has been transported from its native land to Asia, the West Indies, Florida, and islands in the Pacific and Indian Oceans. It is a threat to native snail populations and has been identified as a vector for several human diseases and parasites.
The Australian trumpet is native to the waters off northern Australia, Papua New Guinea and eastern Indonesia. It is known to be carnivorous but little is known about its ecology or behavior.