Snail eating a carrot. (twistypigeon / Flickr; cc by 2.0)

Green Snail, Rhinocochlis nasuta. (Bernard Dupont) / Wiki; cc by-sa 2.0)

A snail’s eye. (Mac Jewell / Flickr; cc by 3.0)

Land snail (Euglandina Rosea). (Tim Ross / Wiki; PD)

Slug and slime trail. (Luis Parravicini / Flickr; cc by-nc-sa 2.0)

Snail eggs. (Chai / Wiki; cc by 2.0)

Snails mating. (Linda / Flickr; cc by 2.0)

A snail’s loopy trail! (Hans / Pixabay; PD)

The underside of Garden Snail, Cornu aspersum, clinging to a plant stem. Note the breathing hole, or pneumostome, in the shell. (Sean Mack / Wiki; cc by 3.0)

The black “dots” at the end of the upper tentacles are eyes. (Gemma Stiles / Flickr; cc by 2.0)