Aliculastrum cylindricum, (common names: cylindrical atys, cylindrical true bubble, silkworm shell), is a species of gastropods belonging to the family Haminoeidae.

(Described as Bulla elongata) The shell is subcylindrical, tapering toward the anterior, with a white, slightly translucent, and glossy surface.

It features transverse striations at both the anterior and posterior ends, while the central area is polished and smooth.

The outer lip is prominently twisted and extended at the posterior end, while the inner lip is somewhat flattened toward the anterior, with a subtle fold.

[3] The marine species has a wide distribution and is found in the Indian and Pacific Oceans, the Red Sea, and off the coast of Australia.