Notogibbula preissiana

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Notogibbula preissiana, commonly known as the twin-keeled top shell, is a small sea snail in the top-shell family Trochidae. It is found in Australian waters off South Australia, Victoria and Western Australia.

The shell is about 7–9 mm tall, thick, and round but slightly flattened, with a deep umbilicus (a hole at the bottom). It has 5 to 5.5 whorls with strong sutures. The shell is white with wavy rosy-brown lines and small spots near the suture and edge. The first whorls are smooth; the later whorls have fine spiral grooves and a raised middle ridge. The last whorl features two keels. The base has concentric ridges, which are larger near the umbilicus. The opening is nearly round, and the columella curves inward without a tooth.