Atys naucum  Atys naucum, common names the "white nut sheath bubble'" and the "Pacific nut sheath bubble", is a species of small tropical sea snail, a bubble snail, a marine opisthobranch gastropod mollusk in the family Haminoeidae, the haminoea bubble snails. The distribution of this species occurs in the Indo-Pacific, off Madagascar, the Red Sea, and also in Australia. It is a common species. The length of the shell of this species is 22–50 mm. In life the shell is light brown and inflated. When the animal dies the periostracum which covers the shell dries out and is lost. Juveniles have brown wavy lines on the shell. This snail is a herbivore.