Analysis of DNA sequences has shown that Smeagol belongs in the family Ellobiidae, and is therefore closely related to ellobiid snails.

[4] The name of the genus is in honour of Tolkien's fictional character Gollum, who was originally known as Sméagol.

[2] In the circulatory system the haemolymph circulates as follows: mantle → nephridium or nephridia[clarification needed] → heart.

[1] Smeagol manneringi is known from the south coast of Wellington, and in a possibly genetically distinct form from Kaikōura.

[7] These slugs inhabit the upper intertidal zone on gravel substrate.