Eyestalk

[1] It is a common feature in nature and frequently appears in fiction.

[2] Eyestalks are a specialized type of tentacle.

Tentacles may also have olfactory organs at their ends.

[3] Examples of creatures with olfactory tentacles include snails, the trilobite superfamily Asaphida, and the fly family Diopsidae.

In slugs and snails, these tentacles will regrow if severely damaged, and in some species, are retractable.

Pulmonate land snails usually have two sets of tentacles on their head: the upper pair have an eye at the end; the lower pair are for olfaction . [ 1 ]