Slug

Slug, mollusk best described as a snail without a shell or with a tiny shell inside the body. An exception is the roundback slug, which has an outside shell. Behind the head, with its 4 tentacles, is an oval shield containing a pore that leads to the lungs. Slugs creep over the ground like snails and leave a trail of slime. As they have no shell to retire into, they have to live in moist places to escape drying up. Some slugs eat fungi, others eat green plants and are garden pests.