Slug

Shell-less terrestrial gastropod mollusc

Slug or land slug is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to gastropods that have a coiled shell large enough that they can fully retract their soft parts into it). Various taxonomic families of land slugs form part of several quite different evolutionary lineages, which also include snails.

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