Pernastela gnoma, also known as the dwarf pinhead snail, is a tiny species of land snail that is endemic to Australia's Lord Howe Island in the Tasman Sea.

[2] The trochoidal shell of the mature snail is 0.8 mm in height, with a diameter of 1.2–1.3 mm, and a moderate spire.

The whorls are shouldered and sutures impressed, with moderately spaced radial ribs.

It has an ovately lunate aperture and a narrow umbilicus.

[2] The snail is common and widespread across the island, inhabiting plant litter.