headfoot
The head-foot is the part you see most easily in slugs and snails. It is mostly a muscular organ covered in cilia and rich in mucous cells, which the mollusc uses to move around, it normally tapers to a tail at one end and has a head incorporated in the front. The head includes a mouth, eyes and tentacles, the last two may be much reduced or even absent. In those species with shells the head-foot can be drawn into the shell.