Slugs

Slugs are gastropod molluscs, which is a fancy way of saying, "Gross, slimy little critters". They are kind of like snails, but they don't have a shell. Common slugs are terrestrial animals, thriving on land, but there are also an amphibious genus of the species known as sea slugs.

Slugs' bodies are made up mostly of water, and without a full-sized shell, their soft tissues are prone to desiccation. They must generate protective mucus to survive. Many species are most active just after rain because of the moist ground. In drier conditions, they hide in damp places such as under tree bark, fallen logs, rocks, and man-made structures, such as planters, to help retain body moisture.

Slugs do not play a major role in speculative fiction and are used primarily to evoke a visceral reaction from film viewers or book readers. In the 1988 horror movie Slugs, a strain of killer black slug evolved after being exposed to toxic waste. With great number, these slugs proved to be extremely dangerous, killing several people in a small rural community until the neighborhood at large began wising up.