Eatoniella fossa is a species of marine gastropod mollusc in the family Eatoniellidae.

Eatoniella fossa has a solid, smooth shell, with a groove between the inner lip and the molluscs body whorl.

[2] This species is easily distinguished by the channel between the aperture and the body whorl of the mollusc.

[1] The holotype and five paratypes of the species were collected from reasonably deep water in the Whangaroa Harbour, Northland, to the west of Stephenson Island.

[3] In addition to the east coast of the Northland Peninsula, Eatoniella fossa has been identified near Manawatāwhi / Three Kings Islands,[4] the Hen and Chicken Islands,[5] and the Bay of Plenty, as far east as Hicks Bay.