Hedleyoconcha addita, also known as the Lord Howe Island conical pinwheel snail, is a species of pinwheel snail that is endemic to Australia's Lord Howe Island in the Tasman Sea. [1]
The trochoidal shell of adult snails is 5.6 mm in height, with a diameter of 7 mm, with a high conical spire, flat sutures and whorls rounded with a keeled edge. It is smooth and pale golden-brown. The umbilicus is narrowly open, partly concealed by the reflected lip of the roundly lunate aperture.[2]
The snail occurs only at the southern end of the island, on the summit of Mount Gower and nearby ledges.[2]